Physics Unit 3 Practice Exam

Consider the situation where there are three forces acting on an object. F1,x = 10.0 N, F2,x = -8.0 N and Fx,3 = -15.0 N. The object has a mass of 3.2 kg. What is the acceleration of the object?

-4.06 m/s2

Claire increases her velocity from 0.25 m/s to 3.25 m/s over a time period of 10.0 s. She is walking with constant acceleration. What is her acceleration?

0.300 m/s2

In physics, an object is said to be accelerating when __________________.

1) it is changing direction 2) it is speeding up 3) it is slowing down

T/F An example of constant velocity is a person whose acceleration changes by 2 m/s each second.

false

T/F An object with positive velocity must be speeding up.

false

T/F If an object changes its velocity by the same amount every second, the object is moving with constant velocity.

false

T/F It is possible for acceleration to be negative when change in velocity is positive.

false

T/F When you see a straight line sloping upwards on a position vs. time graph, it means the object has a constant, non-zero, acceleration.

false

Suppose there is a net force in the x direction of 33 N on a box of mass 11 kg. Find acceleration of the box along the x-axis.

3.0 m/s2

A wooden box made of oak is being pulled across a tile floor. The force of gravity on the box is 100.00 N. The coefficient of kinetic friction between oak and tile is 0.32. Find the magnitude of the force of kinetic friction on the box.

32 N

How many forces are there on a box that is on a carpeted floor and being dragged to the right by a pulling force?

4

Convert 67,543 grams to kilograms

67.543

A box is on a table. It has three, x-directed forces on it, listed below. Find the net force in the x direction on the box. F x1 = 19 N; Fx2= -10 N; Fx3 = -1 N

8 N

d

Attached to this card you see a graph of velocity in the x direction vs. time for an object. Which statement is FALSE? a) the acceleration of the object is about 8 m/s2 b) the object's velocity is increasing by about 8 m/s every second c) the object is speeding up d) the position vs. time graph for the object (not shown) is a straight line with positive slope e) the acceleration vs. time graph for the object (not shown) is a horizontal line at 8 m/s2

Under what condition will an object be in equilibrium?

If the object is either at rest or moving with constant velocity

The data table describes Mia's velocity. What does this say about her velocity? Time | velocity 0 | 3.4 1 | 2.9 2 | 2.4 3 | 1.9 4 | 1.4 5 | .9 6 | .4

Mia is moving with constant negative acceleration.

Which of the following situations is impossible? a) An object has a constant non-zero velocity and changing acceleration. b) An object has zero velocity but a non-zero acceleration. c) An object has constant non-zero acceleration and changing velocity d) An object has velocity directed east and acceleration directed west.

a

If a person is walking in the positive x direction at constant velocity ... a) her position vs. time graph will be a straight line sloping downwards b) her velocity vs. time graph will be a horizontal line at a positive velocity c) her acceleration graph will be a horizontal line at a positive acceleration

b

Which dot diagram below represents an object that is speeding up? a) ........ b) .. . . . . . . . c) . . . . . . . . .

b or c

Which of the following units simplifies to m/s2 and is thus a possible unit for acceleration (remainder of question is on the other side of the card)?

both a and b

Suppose you see a block being pulled across a horizontal tabletop. Which statement is FALSE? a) the velocity of the block in the y direction is zero b) the position of the block along the y-axis is constant c) the acceleration in the y direction is zero d) the normal force is stronger than the force of gravity e) the net force in the y direction is zero

d

Which of the following is NOT a valid conclusion to draw from Newton's 2nd Law? a) When you see an object with only one force on it, the object must be accelerating b) If there is no net force on an object is zero, that object will either be at rest or will be moving with constant velocity c) When the net force on an object is zero, that object will either be at rest or will be moving with constant velocity d) An object with a net force on it of 5N, will have an acceleration of 5 m/s2 e) When the net force of an object is not zero, the object's velocity must be changing.

d

Suppose you go to Caroline's house. Emma answers the door and tells you that Caroline is in the living room pushing on the sofa. Then you know for sure that.... a) the sofa is at rest b) the sofa is moving c) the sofa is moving with constant velocity d) the sofa is accelerating e) you don't know any of these for sure

e

T/F A person who is walking with a constant velocity of 1 m/s has zero acceleration.

true

T/F Acceleration is a measure of how fast the velocity of an object is changing, and in what direction.

true

T/F Acceleration is positive whenever change in velocity is positive.

true

T/F Acceleration must be zero if velocity is constant.

true

T/F Constant velocity means that the position of the object changes by the same amount each second.

true

T/F It is possible for acceleration to be negative when change in velocity is negative.

true

T/F Velocity is a measure of how fast the position of an object is changing, and in what direction.

true

T/F When an object is accelerating, the object's velocity is changing.

true

T/F When you pull a block along a horizontal tabletop at constant velocity, it must be that the force of friction and the pulling force are balanced, i.e., that those two forces must add to zero.

true

T/F When you pull a block and it accelerates towards you, you know that the pulling force is greater than the force of friction.

true

T/F When you pull on a block with a small force and the block does NOT begin to move, you know that the pulling force and the force of friction are balanced, i.e., that those two forces must add to zero.

true