Physics movement questions and solutions

8/12/2019 Physics movement questions and solutions

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Name: ______________________________________________________________ Total Points: _______

(Last) (First)

Multiple choice questions

Answer all of the following questions. Read each question carefully. Fill the correctbubble on your scantron sheet. Each question has exactly one correct answer. All

questions are worth the same amount of points.

A plane goes 300 km from A to B in a straight line, immediately turns

around, and returns to A. The time for this round trip is 2 hour. The

magnitude of the average velocity of the plane for this round trip is

A.

0 km/ht

xvavg

= and 0=x

B. 100 km/hC. 150 km/h

D. 200 km/h

1.

E. Cannot be calculated without knowing the acceleration

A car, initially at rest, travels 20m in 4s along a straight line with

constant acceleration. The acceleration of the car (in m/s2) is

A. 0.4B. 1.3C.

2.52

2/5.2

2sm

t

xa ==

D. 4.9

2.

E. 9.8

At a stoplight, a truck traveling at 15m/s passes a car as it starts from

rest. The truck travels at constant velocity and the car accelerates at

3m/s2. How many seconds will it take for the car to catch up to the

truck?

A. 5

B.10 txtruck 15= ,

2321 txcar = , statxx truckcar 10==

C. 15

D. 20

3.

E. 25


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(Last) (First)

An elevator is moving upward with constant acceleration. The

dashed curve shows the position y of the ceiling of the elevator as a

function of the time t. At the instant indicated by the dot, a bolt

breaks loose and drops from the ceiling. Which curve best represents

the position of the bolt as a function of time?

4.

y

t

A The trajectory must be

a parabola. When the

bolt breaks loose, the

elevator and the bolt

have the same velocity

(the bolt parabola

should have the same

tangent as the elevator

trajectory at the dot)

C

DE

B


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(Last) (First)

On a circular track, a car starts from rest at point A and moves in a

clockwise direction with increasing speed. What is the direction of

the acceleration vector at A?

A. Undefined: the acceleration is zero

B.

C.

D.

5.

E.

A

B

cAC vvvv rrrr

== Take C between A and B and bring

it closer and closer to A. Cvr

becomes tangent to the

circle at A ointed u .


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(Last) (First)

Referring to the car of the previous question, what would be a valid

direction of the acceleration at point B?

A. Undefined: the acceleration is zero

B.

C. The car is traveling on a circle: one component of the acceleration

is toward the center. The car is speeding up: the other component

of the acceleration is tangent to the circle.

D.

6.

E.

Four vectors DCBArrrr

,,, all have the same magnitude. The angle

between adjacent vectors is 45as shown. The correct vector

equation is

A. 0=+ DCBArrrr

B.

02 =+ DCBrrr

Add Br

and Dr

using the parallelogram construction. The sum

DBrr

+ is equal to Cr

2

C. DBBArrrr

+=+

D. 0=+++ DCBArrrr

7.

E. 02 =++ CBArrr

Ar

Br

Cr

Dr

45

45

45


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(Last) (First)

In the diagram, Ar

has magnitude 12 m and Br

has magnitude 8 m.

The x component of BArr

+ is about

A. 4.5 mB. 8.5 mC. 12.5 m since Ax+Bx=12cos45 + 8cos60

D. 14.5 m

8.

E. 20 m

x

45

60

Ar

Br

y


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(Last) (First)

Two objects, A and B, move with constant speed relative to a straight

line. The strobe diagram shows the positions of the objects at instant

1-3, separated by one-second time intervals. (Note that each tick mark

on the diagram represents 5 meters.)

At instant 2 what is the direction of the instantaneous velocity of object

B in the frame of reference of object A?

A. to the left (B is getting closer and closer to A)B. to the rightC. Undefined: the velocity is zero

9.

Still referring to the problem of the previous question, at instant 2, what

is the magnitude of the instantaneous velocity of object B in the frame

of reference of object A?

A. 0 m/sB. 10 m/s

Between instant 1 and instant 2, the distance between A and B

changes from 20m to 10mC. 20 m/sD. 30 m/s

10.

E. 50 m/s

B

AAA

B B

1

1

2

2

3

35 meters


7/10


(Last) (First)

Questions 11 through 18 all refer to the same problem.

A baseball is thrown from the top of a cliff as shown below. The cliff height

is marked in each case. Answer the following questions, referring to these

cases. Take g=10 m/s2.

In which case will the baseball remain in the air the longest amount of

time? D

It is case D that has the largest initial v0y

11.

45

x

y

5 m/s

20 m

45

A

20 m/s

20 m

B

5 m/s

20 m

C

30 m/s

20 m

E

10 m/s

20 m

D (Assume that the ball

doesn't touch the cliff

on its way down).


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(Last) (First)

In which case will the baseball remain in the air the shortest amount

of time? C

It is case C that has the smallest initial v0y(since v0y


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(Last) (First)

If you wanted to make the ball go farther in the x direction, in case B, you

could

A. increase the magnitude of the initial velocity

OK since the distance is timeflightx tv 0 . A greater initial velocity increases

v0xB. change the angle between the initial velocity and the x direction to +45

(i.e. the initial velocity is directed upward at a 45angle).

If the projectile is fired at an angle at the top of a cliff of height h, the

flight time is the (positive) solution of

g

h

g

v

g

vttvgth

2sinsinsin

2

12

22

00

0

2++=+=

and the distance traveled is

g

h

g

vv

g

vd

2sincos

cossin2

22

00

2

0++=

Thus

mg

h

g

vv

g

vd

mg

hvd

6.542

222

4010

4020

2

2

2

00

2

045

00

=++=

===

=

=

C. move to a higher cliffOK since the distance is timeflightx tv 0 . A higher cliff increases tflight time

D. A and B

15.

E. A, B and C

All questions 16 through 18 refers to case D (take g=10m/s2)


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(Last) (First)

Determine how many seconds it takes for the baseball to hit the ground

A. 1.9B. 2.7

C. 3.2Solve:

=+=+= 5110102

120 2 ttt

D. 3.8

16.

E. 4.8

What is the magnitude of the velocity when the ball hits the ground?

A.0 m/sB. 5 m/s

C. 10.7 m/sD. 15.8 m/s

17.

E. 22.4 m/s

There is only motion along the y axis andsmvtvv y /36.221010 =+==

What is the direction of the acceleration when the baseball is at its

highest point?

A. Undefined: the acceleration is zero.B. xC. xD. y

18.

E. y

The acceleration of the ball is always equal to the acceleration of

gravity

Physics movement questions and solutions

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