Question 1

Velocity is defined as:
A) rate of change of position with time
B) position divided by time
C) rate of change of acceleration with time
D) a speeding up or slowing down
E) change of position

Accepted Answer

Velocity is defined as the rate of change of position with time. This means that it is the speed at which an object is moving in a particular direction.

Question 2

A bomber flying in level flight with constant velocity releases a bomb before it is over the target. Neglecting air resistance, which one of the following is NOT true?
A) The bomber is over the target when the bomb strikes
B) The acceleration of the bomb is constant
C) The horizontal velocity of the plane equals the vertical velocity of the bomb when it hits the target
D) The bomb travels in a curved path
E) The time of flight of the bomb is independent of the horizontal speed of the plane

Accepted Answer

C

Question 3

A ball is thrown horizontally from the top of a 20-m high hill. It strikes the ground at an angle of 45$\degree$. With what speed was it thrown? 
A) 14 m/s
B) 20 m/s
C) 28 m/s
D) 32 m/s
E) 40 m/s

Accepted Answer

B

Question 4

A boy on the edge of a vertical cliff 20 m high throws a stone horizontally outwards with a speed of 20 m/s. It strikes the ground at what horizontal distance from the foot of the cliff? Use g = 10 m/s² A) 10 m B) 40 m C) 50 m D) E) none of these

Accepted Answer

The answer of A boy on the edge of a...

Question 5

A plane traveling north at 200 m/s turns and then travels south at 200 m/s. The change in its velocity is:
A) zero
B) 200 m/s north
C) 200 m/s south
D) 400 m/s north
E) 400 m/s south

Accepted Answer

The answer of A plane traveling north at 200 m/s...

Question 6

An object is shot from the back of a railroad flatcar moving at 40 km/h on a straight horizontal road. The launcher is aimed upward, perpendicular to the bed of the flatcar. The object falls:
A) in front of the flatcar
B) behind the flatcar
C) on the truck
D) either behind or in front of the flatcar, depending on the initial speed of the object
E) to the side of the flatcar

Accepted Answer

The answer of An object is shot from the back...

Question 7

Which of the following is a vector quantity?
A) Mass
B) Density
C) Speed
D) Temperature
E) None of these

Accepted Answer

Mass, density, speed, and temperature are all scalar quantities because they do not include direction in their measurement. Vector quantities require both magnitude and direction.

Question 8

Two bodies are falling with negligible air resistance, side by side, above a horizontal plane. If one of the bodies is given an additional horizontal acceleration during its descent, it:
A) strikes the plane at the same time as the other body
B) strike the plane earlier than the other body
C) has the vertical component of its velocity altered
D) has the vertical component of its acceleration altered
E) follows a straight line path along the resultant acceleration vector

Accepted Answer

The additional horizontal acceleration does not affect the vertical motion due to gravity, so both bodies hit the ground at the same time. Horizontal and vertical motions are independent in projectile motion.

Question 9

Which of the following is a scalar quantity?
A) Speed
B) Velocity
C) Displacement
D) Acceleration
E) None of these

Accepted Answer

A scalar quantity is a quantity that has only magnitude and no direction. Speed is the measure of the distance traveled per unit time and only has a magnitude, making it a scalar quantity. Velocity and displacement are vector quantities that have both magnitude and direction. Acceleration is also a vector quantity as it has both magnitude and direction. Therefore, the correct answer is A) Speed.

Question 10

A large cannon is fired from ground level over level ground at an angle of 30$\degree$ above the horizontal. The muzzle speed is 980 m/s. Neglecting air resistance, the projectile will travel what horizontal distance before striking the ground?
A) 4.3 km
B) 8.5 km
C) 43 km
D) 85 km
E) 170 km

Accepted Answer

The answer of A large cannon is fired from ground...

Question 11

The velocity of a projectile equals its initial velocity added to:
A) a constant horizontal velocity
B) a constant vertical velocity
C) a constantly increasing horizontal velocity
D) a constantly increasing downward velocity
E) a constant velocity directed at the target

Accepted Answer

The velocity of a projectile changes due to gravity, which constantly increases its downward velocity. Horizontal velocity remains constant if air resistance is neglected.

Question 12

A particle goes from x = -2 m, y = 3 m, z = 1 m to x = 3 m, y = -1 m, z = 4 m. Its displacement is:
A) 
B) 
C) 
D) 
E)

Accepted Answer

To find the displacement, we subtract the initial position vector from the final position vector: <3,-1,4> - <-2,3,1> = <5,-4,3> The magnitude of this vector is: sqrt((5)^2+(-4)^2+(3)^2) = sqrt(50+16+9) = sqrt(75) = 5sqrt(3) Therefore, the displacement is 5sqrt(3) meters in magnitude and is directed from the initial position to the final position. The correct answer choice is B.

Question 13

A bullet shot horizontally from a gun:
A) strikes the ground much later than one dropped vertically from the same point at the same instant
B) never strikes the ground
C) strikes the ground at approximately the same time as one dropped vertically from the same point at the same instant
D) travels in a straight line
E) strikes the ground much sooner than one dropped from the same point at the same instant

Accepted Answer

Both bullets, the one shot horizontally and the one dropped vertically, will hit the ground at the same time because they are affected by the same acceleration due to gravity. The horizontal motion of the bullet shot from the gun does not affect its vertical motion towards the ground.

Question 14

Acceleration is defined as:
A) rate of change of position with time
B) speed divided by time
C) rate of change of velocity with time
D) a speeding up or slowing down
E) change of velocity

Accepted Answer

Acceleration is defined as the rate of change of velocity with time. Velocity includes both speed and direction, so an object can accelerate even if it is not speeding up. Therefore, choice C is the most accurate definition of acceleration.

Question 15

A stone is thrown outward from the top of a 59.4-m high cliff with an upward velocity component of 19.5 m/s. How long is stone in the air?
A) 4.00 s
B) 5.00 s
C) 6.00 s
D) 7.00 s
E) 8.00 s

Accepted Answer

Using the kinematic equations of motion, we can find the time it takes for the stone to reach the ground. The equation we need is:
y = viy*t + (1/2)at^2
where y is the height, viy is the initial velocity in the y-direction, a is acceleration due to gravity (-9.81 m/s^2), and t is time.
Plugging in the values:
-59.4 m = (19.5 m/s)t + (1/2)(-9.81 m/s^2)t^2
Simplifying:
-4.905t^2 + 19.5t - 59.4 = 0
Using the quadratic formula:
t = (-19.5 ± sqrt(19.5^2 - 4(-4.905)(-59.4))) / (2(-4.905))
t = 6.03 s (ignoring the negative root)
Therefore, the stone is in the air for approximately 6.00 seconds. So, the answer is C).

Question 16

Identical guns fire identical bullets horizontally at the same speed from the same height above level planes, one on the Earth and one on the Moon. Which of the following three statements is/are true? I. The horizontal distance traveled by the bullet is greater for the Moon.
II) The flight time is less for the bullet on the Earth.
III) The velocities of the bullets at impact are the same.
A) III only
B) I and II only
C) I and III only
D) II and III only
E) I, II, III

Accepted Answer

I) The horizontal distance traveled by the bullet is greater for the Moon because the gravitational pull of the Moon is weaker than that of Earth, which means there is less force acting against the bullet’s motion, allowing it to travel farther. 
II) The flight time is less for the bullet on the Earth because the acceleration due to gravity is greater, which increases the speed of the bullet and decreases the time it takes to reach its target. 
III) The velocities of the bullets at impact are the same because the initial speed of the bullets are the same and air resistance is negligible.

Question 17

The airplane shown is in level flight at an altitude of 0.50 km and a speed of 150 km/h. At what distance d should it release a heavy bomb to hit the target X? Take g = 10 m/s². A) 150 m B) 295 m C) 417 m D) 2550 m E) 15,000 m

Accepted Answer

The answer of The airplane shown is in level flight...

Question 18

A jet plane in straight horizontal flight passes over your head. When it is directly above you, the sound seems to come from a point behind the plane in a direction 30$\degree$ from the vertical. The speed of the plane is:
A) the same as the speed of sound
B) half the speed of sound
C) three-fifths the speed of sound
D) 0.866 times the speed of sound
E) twice the speed of sound

Accepted Answer

The answer of A jet plane in straight horizontal flight...

Question 19

A stone is thrown horizontally and follows the path XYZ shown. The direction of the acceleration of the stone at point Y is: 
A) $\downarrow$
B) $\rightarrow$
C) 
D) 
E)

Accepted Answer

The answer of A stone is thrown horizontally and follows...

Question 20

Which of the following is NOT an example of accelerated motion?
A) Vertical component of projectile motion
B) Circular motion at constant speed
C) A swinging pendulum
D) Earth's motion about sun
E) Horizontal component of projectile motion

Accepted Answer

The horizontal component of projectile motion is not an example of accelerated motion because it remains constant if air resistance is neglected. Acceleration occurs in the vertical direction due to gravity, but not horizontally.

Quiz 4: Motion in Two and Three Dimensions

Velocity is defined as:

A bomber flying in level flight with constant velocity releases a bomb before it is over the target. Neglecting air resistance, which one of the following is NOT true?

A boy on the edge of a vertical cliff 20 m high throws a stone horizontally outwards with a speed of 20 m/s. It strikes the ground at what horizontal distance from the foot of the cliff? Use g = 10 m/s²

A plane traveling north at 200 m/s turns and then travels south at 200 m/s. The change in its velocity is:

An object is shot from the back of a railroad flatcar moving at 40 km/h on a straight horizontal road. The launcher is aimed upward, perpendicular to the bed of the flatcar. The object falls:

Which of the following is a vector quantity?

Two bodies are falling with negligible air resistance, side by side, above a horizontal plane. If one of the bodies is given an additional horizontal acceleration during its descent, it:

Which of the following is a scalar quantity?

A large cannon is fired from ground level over level ground at an angle of 30 $\degree$ above the horizontal. The muzzle speed is 980 m/s. Neglecting air resistance, the projectile will travel what horizontal distance before striking the ground?

The velocity of a projectile equals its initial velocity added to:

A particle goes from x = -2 m, y = 3 m, z = 1 m to x = 3 m, y = -1 m, z = 4 m. Its displacement is:

A bullet shot horizontally from a gun:

Acceleration is defined as:

A stone is thrown outward from the top of a 59.4-m high cliff with an upward velocity component of 19.5 m/s. How long is stone in the air?

The airplane shown is in level flight at an altitude of 0.50 km and a speed of 150 km/h. At what distance d should it release a heavy bomb to hit the target X? Take g = 10 m/s².

A jet plane in straight horizontal flight passes over your head. When it is directly above you, the sound seems to come from a point behind the plane in a direction 30 $\degree$ from the vertical. The speed of the plane is:

A stone is thrown horizontally and follows the path XYZ shown. The direction of the acceleration of the stone at point Y is: $A stone is thrown horizontally and follows the path XYZ shown. The direction of the acceleration of the stone at point Y is: A) \downarrow B) \rightarrow C) D) E)$

Which of the following is NOT an example of accelerated motion?