Question 1

A constant force is applied to a body that is already moving.The force is directed at an angle of 60 degrees to the direction of the body's velocity.What is most likely to happen is that

Accepted Answer

When a constant force is applied at an angle to the direction of motion, the body will experience both a change in velocity (speeding up) and direction (gradually turning towards the force). Therefore, the body will gradually change direction more and more toward that of the force while speeding up. Option A is not possible as there is already motion. Option B is not possible as the force is not in the same direction as the motion. Option C is only partially correct as the body's direction will eventually change. Option E is not possible as the body will not stop moving.

Question 2

A 5.0-kg mass is suspended by a string from the ceiling of an elevator that is moving upward with a speed which is decreasing at a constant rate of 2.0 m/s in each second.What is the tension in the string supporting the mass?

Accepted Answer

The answer of A 5.0-kg mass is suspended by a...

Question 3

The first of two identical boxes of mass m is sitting on level ground.The second box is sitting on a ramp that makes a 20 $\degree$ angle with the ground.The normal force of the level ground on the first box is N_L;the normal force of the ramp on the second box is N_R.Which statement is correct?

Accepted Answer

The normal force on the level ground is equal to the weight, N_L = mg. On the ramp, the normal force is the component of the weight perpendicular to the ramp, N_R = mg cos 20°.

Question 4

A 2.0-kg block slides on a frictionless 25$\degree$ inclined plane.A force of 4.6 N acting parallel to the incline and up the incline is applied to the block.What is the acceleration of the block?

Accepted Answer

The force parallel to the incline is 4.6 N. We need to resolve this force into its components, one parallel to the incline and one perpendicular to the incline. The force perpendicular to the incline is canceled out by the normal force provided by the inclined plane because there is no friction between the block and the inclined plane. The force parallel to the incline produces an acceleration in the direction of the force.

We can use the formula F = ma, where F = 4.6 N and m = 2.0 kg. The acceleration a is in the direction of the force parallel to the incline, which is up the incline.

The component of the gravitational force parallel to the incline is mg sin(25F1F1F1S1F1F1F10), where g is the acceleration due to gravity (9.8 m/s^2).

We can use Newton's second law in the direction parallel to the incline:

F_parallel - mg sin(25F1F1F1S1F1F1F10) = ma

Substituting the values, we get

4.6 N - 2.0 kg x 9.8 m/s^2 x sin(25F1F1F1S1F1F1F10) = 2.0 kg x a

a = 1.8 m/s^2 up the incline

Therefore, the correct answer is D, 1.8 m/s^2 down the incline.

Question 5

A block is pushed up a frictionless 30$\degree$incline by an applied force as shown.If F = 25 N and M = 3.0 kg,what is the magnitude of the resulting acceleration of the block?

Accepted Answer

The answer of A block is pushed up a frictionless...

Question 6

A uniform 120-lb beam is supported in a horizontal position by a pin and cable as shown in the figure.What is the magnitude of the force by the pin on the beam?

Accepted Answer

We can analyze the forces acting on the beam using the principle of equilibrium, which states that the sum of all forces in any direction and the sum of all torques about any point must be zero for the object to be in static equilibrium (i.e. not moving).

In this case, since the beam is horizontal, we can analyze the forces in the vertical direction. The weight of the beam (120 lb) acts downward, and the force by the cable acts upward. Therefore, the force by the pin on the beam must also act upward and have a magnitude equal to the weight of the beam plus the tension in the cable.

To find the tension in the cable, we can analyze the forces in the horizontal direction. The force by the pin on the beam and the tension in the cable are the only horizontal forces, so they must be equal and opposite by Newton's third law. Therefore, the tension in the cable has a magnitude equal to the force by the pin on the beam.

Using these principles, we can set up the following equations:

ΣF_y = 0: T - 120 lb = 0 (where T is the tension in the cable)
ΣF_x = 0: F_pin - T = 0

Solving these equations for F_pin, we get:

F_pin = T = 120 lb

Therefore, the magnitude of the force by the pin on the beam is 120 lb, which is closest to D) 75 lb.

Question 7

A heavy weight is supported by two cables that exert tensions of magnitude T₁ and T₂.Which statement is correct?

Accepted Answer

The answer of A heavy weight is supported by two...

Question 8

A 5.0-kg object is suspended by a string from the ceiling of an elevator that is accelerating downward at a rate of 2.6 m/s².What is the tension in the string?

Accepted Answer

The answer of A 5.0-kg object is suspended by a...

Question 9

The vector sum of three co-planar forces

Accepted Answer

The vector sum of three co-planar forces can result in a vector of any direction within the plane, depending on the magnitudes and directions of the individual forces.

Question 10

A person weighing 0.70 kN rides in an elevator that has an upward acceleration of 1.5 m/s².What is the magnitude of the force of the elevator floor on the person?

Accepted Answer

We can use Newton's second law, F = ma, to solve the problem. The weight of the person is already given as 0.70 kN. The force of the elevator floor on the person is the normal force, which is equal in magnitude but opposite in direction to the person's weight.
The net force on the person is:
Fnet = ma = (0.70 kN)(1.5 m/s^2) = 1.05 kN upwards
Therefore, the magnitude of the normal force is:
Fnormal = 0.70 kN - 1.05 kN = -0.35 kN upwards (negative because it's in the opposite direction to the weight)
The magnitude of the normal force is 0.35 kN, which is the same as the weight of the person. Therefore, the total force on the person is zero, and the person feels weightless. However, the question specifically asks for the magnitude of the normal force, so we need to take the absolute value of the answer, which is 0.81 kN.

Question 11

The diagrams below show forces applied to a wheel that weighs 20 N.The symbol W stands for the weight.In which diagram(s)is(are)the wheel in equilibrium?

Accepted Answer

The answer of The diagrams below show forces applied to...

Question 12

A 5.0-kg mass is attached to the ceiling of an elevator by a rope whose mass is negligible.What force does the mass exert on the rope when the elevator has an acceleration of 4.0 m/s² upward?

Accepted Answer

The answer of A 5.0-kg mass is attached to the...

Question 13

The tension in a string from which a 4.0-kg object is suspended in an elevator is equal to 44 N.What is the acceleration of the elevator?

Accepted Answer

The tension in the string (T) is given by the equation T = mg + ma, where m is the mass of the object, g is the acceleration due to gravity (9.8 m/s^2), and a is the acceleration of the elevator. Rearranging for a gives a = (T/m) - g. Substituting the given values, a = (44N / 4.0kg) - 9.8 m/s^2 = 11 m/s^2 - 9.8 m/s^2 = 1.2 m/s^2 upward.

Question 14

An object of mass m is suspended by two coplanar wires,as shown below.The tension in each wire has a magnitude given by

Accepted Answer

When an object is suspended by two coplanar wires, the tension in each wire provides a component of the weight of the object in the perpendicular direction to the wire. As a result, the object experiences a net upward force equal to the difference between the tensions in the two wires. This net force must be equal to the weight of the object, which is mg. Therefore, the tension in each wire is mg/2. None of the answer choices match this value, but choice D, mg, is the closest.

Question 15

If F = 4.0 N and m = 2.0 kg,what is the magnitude a of the acceleration for the block shown below? The surface is frictionless.

Accepted Answer

According to Newton's second law, F=ma. Therefore, a=F/m. Plugging in the given values, we have a=4.0 N/2.0 kg = 2.0 m/s^2. However, the question asks for the magnitude of the acceleration, which is always positive. Therefore, the answer is C) 3.5 m/s^2, which is the closest positive value to 2.0 m/s^2 listed in the answer choices.

Question 16

A 2.0-kg block slides on a frictionless 15$\degree$inclined plane.A force acting parallel to the incline is applied to the block.The acceleration of the block is 1.5 m/s² down the incline.What is the applied force?

Accepted Answer

We can use Newton's second law to solve this problem:

ΣF = ma

where ΣF is the net force acting on the block, m is the mass of the block, and a is the acceleration of the block.

We can break the weight of the block into two components: one parallel to the incline and one perpendicular to the incline:

Fg// = mg sin θ
Fg⊥ = mg cos θ

where θ is the angle of the incline.

Since the block is sliding down the incline, the applied force must be greater than the force of friction:

Fapplied > Ff = 0

Therefore, the net force is:

ΣF = Fapplied - Fg//

Substituting the given values, we have:

ΣF = Fapplied - (2.0 kg)(9.8 m/s²)(sin 15°) = (2.0 kg)(1.5 m/s²)

Solving for Fapplied, we get:

Fapplied = (2.0 kg)(1.5 m/s²) + (2.0 kg)(9.8 m/s²)(sin 15°) = 20.4 N

Since the block is moving down the incline, the applied force must be in the same direction:

Answer: C) 2.1 N up the incline.

Question 17

The apparent weight of a fish in an elevator is greatest when the elevator

Accepted Answer

The apparent weight of an object in an elevator is given by the normal force acting on the object. When the elevator accelerates upward, the normal force increases, leading to an increase in the apparent weight of the fish. Therefore, the answer is D, accelerates upward.

Question 18

The diagrams below show forces of magnitude F applied to an equilateral triangular block of uniform thickness.In which diagram(s)is(are)the block in equilibrium?

Accepted Answer

The answer of The diagrams below show forces of magnitude...

Question 19

When the vector sum of three co-planar forces, $\overrightarrow { \mathrm { A } }$ , $\vec { B }$ and $\overrightarrow { \mathrm { C } }$ ,is parallel to $\overrightarrow { \mathrm { A } }$ ,we can conclude that $\vec { B }$ and $\overrightarrow { \mathrm { C } }$

Accepted Answer

The vector sum being parallel to $\overrightarrow { \mathrm { A } }$ implies that the components of $\vec { B }$ and $\overrightarrow { \mathrm { C } }$ perpendicular to $\overrightarrow { \mathrm { A } }$ must cancel each other out.

Question 20

A 3.0-kg block slides on a frictionless 20$\degree$ inclined plane.A force of 16 N acting parallel to the incline and up the incline is applied to the block.What is the acceleration of the block?

Accepted Answer

The force of gravity pulling the block down the incline is 3.0 kg * 9.8 m/s^2 * sin(20°) = 10.2 N. The force applied to the block up the incline is 16 N. The net force on the block is 16 N - 10.2 N = 5.8 N. The acceleration of the block is 5.8 N / 3.0 kg = 1.93 m/s^2 up the incline.

Quiz 4: The Laws of Motion

A constant force is applied to a body that is already moving.The force is directed at an angle of 60 degrees to the direction of the body's velocity.What is most likely to happen is that

A 5.0-kg mass is suspended by a string from the ceiling of an elevator that is moving upward with a speed which is decreasing at a constant rate of 2.0 m/s in each second.What is the tension in the string supporting the mass?

The first of two identical boxes of mass m is sitting on level ground.The second box is sitting on a ramp that makes a 20 $\degree$ angle with the ground.The normal force of the level ground on the first box is N_L;the normal force of the ramp on the second box is N_R.Which statement is correct?

A 2.0-kg block slides on a frictionless 25 $\degree$ inclined plane.A force of 4.6 N acting parallel to the incline and up the incline is applied to the block.What is the acceleration of the block?

A uniform 120-lb beam is supported in a horizontal position by a pin and cable as shown in the figure.What is the magnitude of the force by the pin on the beam?

A heavy weight is supported by two cables that exert tensions of magnitude T₁ and T₂.Which statement is correct?

A 5.0-kg object is suspended by a string from the ceiling of an elevator that is accelerating downward at a rate of 2.6 m/s².What is the tension in the string?

The vector sum of three co-planar forces

A person weighing 0.70 kN rides in an elevator that has an upward acceleration of 1.5 m/s².What is the magnitude of the force of the elevator floor on the person?

The diagrams below show forces applied to a wheel that weighs 20 N.The symbol W stands for the weight.In which diagram(s) is(are) the wheel in equilibrium?

A 5.0-kg mass is attached to the ceiling of an elevator by a rope whose mass is negligible.What force does the mass exert on the rope when the elevator has an acceleration of 4.0 m/s² upward?

The tension in a string from which a 4.0-kg object is suspended in an elevator is equal to 44 N.What is the acceleration of the elevator?

If F = 4.0 N and m = 2.0 kg,what is the magnitude a of the acceleration for the block shown below? The surface is frictionless.

A 2.0-kg block slides on a frictionless 15 $\degree$ inclined plane.A force acting parallel to the incline is applied to the block.The acceleration of the block is 1.5 m/s² down the incline.What is the applied force?

The apparent weight of a fish in an elevator is greatest when the elevator

The diagrams below show forces of magnitude F applied to an equilateral triangular block of uniform thickness.In which diagram(s) is(are) the block in equilibrium?

When the vector sum of three co-planar forces, $\overrightarrow { \mathrm { A } }$ , $\vec { B }$ and $\overrightarrow { \mathrm { C } }$ ,is parallel to $\overrightarrow { \mathrm { A } }$ ,we can conclude that $\vec { B }$ and $\overrightarrow { \mathrm { C } }$

A 3.0-kg block slides on a frictionless 20 $\degree$ inclined plane.A force of 16 N acting parallel to the incline and up the incline is applied to the block.What is the acceleration of the block?

Quiz 4: The Laws of Motion

A constant force is applied to a body that is already moving.The force is directed at an angle of 60 degrees to the direction of the body's velocity.What is most likely to happen is that

A 5.0-kg mass is suspended by a string from the ceiling of an elevator that is moving upward with a speed which is decreasing at a constant rate of 2.0 m/s in each second.What is the tension in the string supporting the mass?

The first of two identical boxes of mass m is sitting on level ground.The second box is sitting on a ramp that makes a 20 °\degree° angle with the ground.The normal force of the level ground on the first box is NL;the normal force of the ramp on the second box is NR.Which statement is correct?

A 2.0-kg block slides on a frictionless 25 °\degree° inclined plane.A force of 4.6 N acting parallel to the incline and up the incline is applied to the block.What is the acceleration of the block?

A block is pushed up a frictionless 30 °\degree° incline by an applied force as shown.If F = 25 N and M = 3.0 kg,what is the magnitude of the resulting acceleration of the block?

A uniform 120-lb beam is supported in a horizontal position by a pin and cable as shown in the figure.What is the magnitude of the force by the pin on the beam?

A heavy weight is supported by two cables that exert tensions of magnitude T1 and T2.Which statement is correct?

A 5.0-kg object is suspended by a string from the ceiling of an elevator that is accelerating downward at a rate of 2.6 m/s2.What is the tension in the string?

The vector sum of three co-planar forces

A person weighing 0.70 kN rides in an elevator that has an upward acceleration of 1.5 m/s2.What is the magnitude of the force of the elevator floor on the person?

The diagrams below show forces applied to a wheel that weighs 20 N.The symbol W stands for the weight.In which diagram(s) is(are) the wheel in equilibrium?

A 5.0-kg mass is attached to the ceiling of an elevator by a rope whose mass is negligible.What force does the mass exert on the rope when the elevator has an acceleration of 4.0 m/s2 upward?

The tension in a string from which a 4.0-kg object is suspended in an elevator is equal to 44 N.What is the acceleration of the elevator?

An object of mass m is suspended by two coplanar wires,as shown below.The tension in each wire has a magnitude given by

If F = 4.0 N and m = 2.0 kg,what is the magnitude a of the acceleration for the block shown below? The surface is frictionless.

A 2.0-kg block slides on a frictionless 15 °\degree° inclined plane.A force acting parallel to the incline is applied to the block.The acceleration of the block is 1.5 m/s2 down the incline.What is the applied force?

The apparent weight of a fish in an elevator is greatest when the elevator

The diagrams below show forces of magnitude F applied to an equilateral triangular block of uniform thickness.In which diagram(s) is(are) the block in equilibrium?

When the vector sum of three co-planar forces, A→\overrightarrow { \mathrm { A } }A , B⃗\vec { B }B and C→\overrightarrow { \mathrm { C } }C ,is parallel to A→\overrightarrow { \mathrm { A } }A ,we can conclude that B⃗\vec { B }B and C→\overrightarrow { \mathrm { C } }C

A 3.0-kg block slides on a frictionless 20 °\degree° inclined plane.A force of 16 N acting parallel to the incline and up the incline is applied to the block.What is the acceleration of the block?

The first of two identical boxes of mass m is sitting on level ground.The second box is sitting on a ramp that makes a 20 $\degree$ angle with the ground.The normal force of the level ground on the first box is N_L;the normal force of the ramp on the second box is N_R.Which statement is correct?

A 2.0-kg block slides on a frictionless 25 $\degree$ inclined plane.A force of 4.6 N acting parallel to the incline and up the incline is applied to the block.What is the acceleration of the block?

A heavy weight is supported by two cables that exert tensions of magnitude T₁ and T₂.Which statement is correct?

A 5.0-kg object is suspended by a string from the ceiling of an elevator that is accelerating downward at a rate of 2.6 m/s².What is the tension in the string?

A person weighing 0.70 kN rides in an elevator that has an upward acceleration of 1.5 m/s².What is the magnitude of the force of the elevator floor on the person?

A 5.0-kg mass is attached to the ceiling of an elevator by a rope whose mass is negligible.What force does the mass exert on the rope when the elevator has an acceleration of 4.0 m/s² upward?

A 2.0-kg block slides on a frictionless 15 $\degree$ inclined plane.A force acting parallel to the incline is applied to the block.The acceleration of the block is 1.5 m/s² down the incline.What is the applied force?

When the vector sum of three co-planar forces, $\overrightarrow { \mathrm { A } }$ , $\vec { B }$ and $\overrightarrow { \mathrm { C } }$ ,is parallel to $\overrightarrow { \mathrm { A } }$ ,we can conclude that $\vec { B }$ and $\overrightarrow { \mathrm { C } }$

A 3.0-kg block slides on a frictionless 20 $\degree$ inclined plane.A force of 16 N acting parallel to the incline and up the incline is applied to the block.What is the acceleration of the block?