Question 1

A 3.0-kg and a 5.0-kg box rest side-by-side on a perfectly smooth, level floor. A horizontal force of 32 N is applied to the 3.0-kg box pushing it against the 5.0-kg box, and, as a result, both boxes slide along the floor. How hard do the two boxes push against each other?
A)12 N
B)20 N
C)24 N
D)32 N
E)0 N

Accepted Answer

The force between the two boxes is equal to the force required to accelerate the 5.0-kg box. Since both boxes move together, they have the same acceleration. The force applied to the 3.0-kg box is 32 N, which accelerates both boxes. The total mass being accelerated is 3.0 kg + 5.0 kg = 8.0 kg. The force between the boxes can be found by using Newton's second law, $F = ma$, where $F$ is the force applied to the 5.0-kg box, $m$ is its mass, and $a$ is the acceleration of both boxes. The acceleration $a$ can be found from the total force divided by the total mass, $a = \frac{32\,N}{8.0\,kg} = 4.0\,m/s^2$. The force on the 5.0-kg box (which is the same as the force they push against each other due to Newton's third law) is $F = 5.0\,kg \times 4.0\,m/s^2 = 20\,N$.

Question 2

Two forces act on a $55 - \mathrm { kg }$ object. One force has magnitude 65 N directed 59° clockwise from the positive x-axis, and the other has a magnitude 35 N at 32° clockwise from the positive y-axis. What is the magnitude of this object's acceleration? A)1.1 m/s² B)1.3 m/s² C)1.5 m/s² D)1.7 m/s²

Accepted Answer

The correct answer is A because the magnitude of the acceleration is 1.1 m/s^2.

Question 3

A very light wire is used to hang a series of 8.0-kg bricks. This wire will break if the tension in it exceeds 450 N. The bricks are hung one below the other from a hook in the ceiling using this wire, as shown in the figure.
(a)How many whole bricks can be hung without breaking the wire?
(b)If you add one more brick to the number found in part (a), which string will break?

Accepted Answer

The answer of A very light wire is used to...

Question 4

Three objects are connected by weightless flexible strings as shown in the figure. The pulley has no appreciable mass or friction, and the string connected to the block on the horizontal bench pulls on it parallel to the bench surface. The coefficients of friction between the bench and the block on it are µ_s = 0.66 and µ_k = 0.325. You observe that this system remains at rest. (a)Find the mass of the hanging object A. (b)What is the magnitude of the friction force on the block on the bench?

Accepted Answer

The answer of Three objects are connected by weightless flexible...

Question 5

A 10-kg sign is held by two ropes as shown in the figure. What is the tension on rope A? 
A)44 N
B)69 N
C)72 N
D)88 N
E)98 N

Accepted Answer

The answer of A 10-kg sign is held by two...

Question 6

A 30.0-kg load is being held in place using massless wires in the ideal pulley arrangement shown in the figure. What is the magnitude of the force F?

Accepted Answer

The answer of A 30.0-kg load is being held in...

Question 7

A 10.0-kg picture is held in place by two wires, the first one hanging at 50.0° to the left of the vertical and the second one at 45.0° to the right of the vertical. What is the tension in the first wire?
A)69.6 N
B)50.8 N
C)98.1 N
D)69.4 N
E)23.8 N

Accepted Answer

The tension in each wire can be calculated using the following equation:

Tension = (weight of object) / (cosine of angle between wire and vertical)

For the first wire, the angle between the wire and the vertical is 50.0° to the left. Therefore, the tension in the first wire is:

Tension = (10.0 kg)(9.81 m/s^2) / (cos 50.0°)
Tension = 96.66 N

For the second wire, the angle between the wire and the vertical is 45.0° to the right. Therefore, the tension in the second wire is:

Tension = (10.0 kg)(9.81 m/s^2) / (cos 45.0°)
Tension = 98.14 N

Therefore, the tension in the first wire is 96.66 N, which is closest to answer choice A (69.6 N).

Question 8

A 400-kg box is lifted vertically upward with constant velocity by means of two cables pulling at 40.0° on either side of the vertical direction. What is the tension in each cable?
A)231 N
B)400 N
C)800 N
D)2560 N
E)3920 N

Accepted Answer

The answer of A 400-kg box is lifted vertically upward...

Question 9

An object is being acted upon by three forces and moves with a constant velocity. One force is 60 N along the +x-axis, the second is 75 N along a direction making a counterclockwise angle of 150° with the +x-axis.
(a)What is the magnitude of the third force?
(b)What is the direction of the third force, measured clockwise from the +x-axis?

Accepted Answer

The answer of An object is being acted upon by...

Question 10

The figure shows a block of mass M hanging at rest. The light wire fastened to the wall is horizontal and has a tension of 38 N. The wire fastened to the ceiling is also very light, has a tension of $$59 \mathrm {~N} ,$$ and makes an angle ? with the ceiling. Find the angle ?. 
A)50°
B)40°
C)33°
D)65°
E)45°

Accepted Answer

The answer of The figure shows a block of mass...

Question 11

A 3.0-kg and a 5.0-kg box rest side-by-side on a smooth, level floor. A horizontal force of 32 N is applied to the 5.0-kg box pushing it against the 3.0-kg box, and, as a result, both boxes slide along the floor. How hard do the two boxes push against each other?
A)12 N
B)20 N
C)24 N
D)32 N
E)0 N

Accepted Answer

The answer of A 3.0-kg and a 5.0-kg box rest...

Question 12

An object is being acted upon by three forces and as a result moves with a constant velocity. One force is 60.0 N along the +x-axis, and the second is 75.0 N along the +y-axis. What is the magnitude of the third force?
A)135 N
B)15.0 N
C)48.0 N
D)67.5 N
E)96.0 N

Accepted Answer

The answer of An object is being acted upon by...

Question 13

A 5.0-kg block and a 4.0-kg block are connected by a 0.6 kg rod, as shown in the figure. The links between the blocks and the rod are denoted by A and B. A vertical upward force of magnitude F is applied to the upper block. The blocks and rod assembly are moving downward at constant velocity of 85 cm/s.
(a)What is the magnitude of the applied force F?
(b)What magnitude force does link A exert?

Accepted Answer

The answer of A 5.0-kg block and a 4.0-kg block...

Question 14

A piano mover raises a 1000-N piano at a constant speed using a very light rope in a frictionless pulley system, as shown in the figure. With what force is the mover pulling down on the rope? 
A)2000 N
B)1000 N
C)500 N
D)250 N
E)Depends on the speed of the piano.

Accepted Answer

The answer of A piano mover raises a 1000-N piano...

Question 15

As shown in the figure, two blocks are connected by a very light string, and the upper block is pulled upward by a different string. The masses of the upper and lower blocks are 300 g and 240 g, respectively. The string between the blocks will break if its tension exceeds 3.6 N, and the string that pulls the combination upward will break if its tension exceeds 7.8 N.
(a)What is the largest upward acceleration that the blocks can be given without either string breaking?
(b)If the upward acceleration is slightly higher than this, which string breaks, the upper one or the lower one?

Accepted Answer

The answer of As shown in the figure, two blocks...

Question 16

A load is being lifted vertically upwards by means of two cables attached to it. The first cable exerts a force of 600 N at an angle of 35.0° to the left of the vertical. The second cable exerts a force of 1300 N. At what angle to the right of the vertical is the second cable pulling?
A)15.4°
B)16.2°
C)30.8°
D)67.8°
E)75.8°

Accepted Answer

The answer of A load is being lifted vertically upwards...

Question 17

A locomotive is pulling 9 freight cars, each of which is loaded with the same weight. The mass of each loaded car is $37,000 \mathrm {~kg} ,$ and we can neglect friction on these 9 cars. If the train is accelerating forward at $0.81 \mathrm {~m} / \mathrm { s } ^ { 2 }$ on a level track, what is the tension in the coupling between the second and third cars? (The car nearest the locomotive is counted as the first car.)

Accepted Answer

The answer of A locomotive is pulling 9 freight cars,...

Question 18

Three boxes rest side-by-side on a smooth, horizontal floor. Their masses are 5.0 kg, 3.0 kg, and 2.0 kg, with the 3.0-kg mass in the center. A force of 50 N pushes on the 5.0-kg box, which pushes against the other two boxes. What magnitude force does the 5.0-kg box exert on the 3.0-kg box?
A)0 N
B)10 N
C)25 N
D)40 N
E)50 N

Accepted Answer

According to Newton's third law, the force exerted by the 5.0-kg box on the 3.0-kg box must be equal in magnitude and opposite in direction to the force exerted by the 3.0-kg box on the 5.0-kg box. Therefore, we only need to consider the forces acting on the 5.0-kg box. The net force on the 5.0-kg box is given as 50 N. We can use this force to calculate the acceleration of the system using Newton's second law. We assume that the boxes move together without slipping. We can use the equation:
F_net = (m1 + m2 + m3)a
where F_net is the net force, m1 is the mass of the 5.0-kg box, m2 is the mass of the 3.0-kg box, m3 is the mass of the 2.0-kg box, and a is the acceleration of the system.
Plugging in the given values, we get:
50 N = (5.0 kg + 3.0 kg + 2.0 kg) a
a = 5 m/s^2
Now, we can use this acceleration to find the force exerted by the 5.0-kg box on the 3.0-kg box using Newton's second law again. We assume that the 3.0-kg box has only the force exerted by the 5.0-kg box on it. We get:
F = m2 a
where m2 is the mass of the 3.0-kg box.
Plugging in the given values, we get:
F = (3.0 kg)(5 m/s^2) = 15 N
Therefore, the magnitude force exerted by the 5.0-kg box on the 3.0-kg box is 15 N, which is closest to choice C.

Question 19

A tightrope walker walks across a 30-m long wire tied between two poles. The center of the wire is displaced vertically downward by 1.0 m when he is halfway across. If the tension in both halves of the wire at this point is $6294 \mathrm {~N}$ what is the mass of the tightrope walker? Neglect the mass of the wire.
A)85 kg
B)43 kg
C)74 kg
D)91 kg

Accepted Answer

The tension in the wire creates two equal forces acting upward at an angle. Using trigonometry, the vertical component of the tension is $T \sin(\theta)$, where $\theta$ is the angle of the wire with the horizontal. The vertical components must balance the weight of the walker, $mg$. Given the geometry, $\sin(\theta) = \frac{1}{15}$. Thus, $2T \sin(\theta) = mg$, solving for $m$ gives $m = \frac{2 \times 6294 \times \frac{1}{15}}{9.8} \approx 85 \text{ kg}$.

Question 20

A 6.00-kg ornament is held at rest by two light wires that form 30° angles with the vertical, as shown in the figure. An external force of magnitude F acts vertically downward on the ornament. The tension exerted by each of the two wires is denoted by T. A free-body diagram, showing the four forces that act on the box, is shown in the figure. If the magnitude of force F is 410 N, what is the magnitude of the tension T? 
A)271 N
B)235 N
C)188 N
D)376 N
E)470 N

Accepted Answer

The answer of A 6.00-kg ornament is held at rest...

Quiz 5: Applying Newtons Laws

A 3.0-kg and a 5.0-kg box rest side-by-side on a perfectly smooth, level floor. A horizontal force of 32 N is applied to the 3.0-kg box pushing it against the 5.0-kg box, and, as a result, both boxes slide along the floor. How hard do the two boxes push against each other?

Two forces act on a 55−kg55 - \mathrm { kg }55−kg object. One force has magnitude 65 N directed 59° clockwise from the positive x-axis, and the other has a magnitude 35 N at 32° clockwise from the positive y-axis. What is the magnitude of this object's acceleration?

A 10-kg sign is held by two ropes as shown in the figure. What is the tension on rope A?

A 30.0-kg load is being held in place using massless wires in the ideal pulley arrangement shown in the figure. What is the magnitude of the force F?

A 10.0-kg picture is held in place by two wires, the first one hanging at 50.0° to the left of the vertical and the second one at 45.0° to the right of the vertical. What is the tension in the first wire?

A 400-kg box is lifted vertically upward with constant velocity by means of two cables pulling at 40.0° on either side of the vertical direction. What is the tension in each cable?

The figure shows a block of mass M hanging at rest. The light wire fastened to the wall is horizontal and has a tension of 38 N. The wire fastened to the ceiling is also very light, has a tension of 59 N,59 \mathrm {~N} ,59 N, and makes an angle ? with the ceiling. Find the angle ?.

A 3.0-kg and a 5.0-kg box rest side-by-side on a smooth, level floor. A horizontal force of 32 N is applied to the 5.0-kg box pushing it against the 3.0-kg box, and, as a result, both boxes slide along the floor. How hard do the two boxes push against each other?

An object is being acted upon by three forces and as a result moves with a constant velocity. One force is 60.0 N along the +x-axis, and the second is 75.0 N along the +y-axis. What is the magnitude of the third force?

A piano mover raises a 1000-N piano at a constant speed using a very light rope in a frictionless pulley system, as shown in the figure. With what force is the mover pulling down on the rope?

A load is being lifted vertically upwards by means of two cables attached to it. The first cable exerts a force of 600 N at an angle of 35.0° to the left of the vertical. The second cable exerts a force of 1300 N. At what angle to the right of the vertical is the second cable pulling?

Three boxes rest side-by-side on a smooth, horizontal floor. Their masses are 5.0 kg, 3.0 kg, and 2.0 kg, with the 3.0-kg mass in the center. A force of 50 N pushes on the 5.0-kg box, which pushes against the other two boxes. What magnitude force does the 5.0-kg box exert on the 3.0-kg box?

Two forces act on a $55 - \mathrm { kg }$ object. One force has magnitude 65 N directed 59° clockwise from the positive x-axis, and the other has a magnitude 35 N at 32° clockwise from the positive y-axis. What is the magnitude of this object's acceleration?