Physics midterm

The net force is dependent on mass and _.

Acceleration

A body that is motionless remains motionless unless a(n) ___ of enough magnitude is acted upon it.

Force

“A body that is motionless remains motionless unless a(n) ___ of enough magnitude is acted upon it.” This question is a part of ____.

Newton’s First Law

An object is moving to the right at a constant speed of 20 m/s. The net force acting on the object is ___.

Zero

An object is slowing down as it is moving to the right, the net force acting on the object is ___.

Pointing left

The force that counteracts gravity for an object sitting on a flat surface is called ___.

Normal force

If I push down on an object that weighs 10 N with an applied force of 15 N and it does not move, the normal force is __.

25 N

An object experiencing a negative force while moving forward must be ___.

Slowing down

An object with a weight of 19.62 N is pushed with a force of 8 N and accelerates at 4 m/s². What is the coefficient of friction?

0

A mass of 20 kg would experience force of friction than a 40 kg mass on the same surface.

Lower

The force of friction is dependent on the coefficient of friction and __.

Normal force

The instant a man jumps from the Eiffel Tower, the drag force he would experience would be .

Zero

An object is at terminal velocity when __.

The drag force equals the force of gravity

A bully holds a 50 kg freshman against the locker. The coefficient of friction is 0.2. How much force must the bully push with?

2455 N

For this free body diagram, Fnet must equal __.

5 N to the left

For this free body diagram, the left force is most close to __.

50 N

The net force for an object moving forward and speeding up is _.

Positive

What is the physical result of the energy lost due to friction?

Energy is converted into heat

(True or False) It typically takes less force to get something moving than it does to keep it moving.

False

(True or False) kg·m/s² is an acceptable unit for force.

True

(True or False) The static force of friction can only oppose an applied force.

True

(True or False) The dynamic force of friction can only oppose an applied force.

False

(True or False) The static coefficient of friction will always be greater than the dynamic coefficient of friction.

True

(True or False) The force of tension will always be a pull.

True

(True or False) Projectile motion is another way of saying motion in two dimensions.

True

(True or False) Vectors in two dimensions can be broken into two components and analyzed individually.

True

(True or False) A projectile has its maximum speed just after it is struck and just before it hits the ground.

True

(True or False) A projectile has its minimum speed at its apex.

True

(True or False) The velocity in the y dimension for a projectile shot at 45° equals the velocity in the x dimension.

True

(True or False) The velocity in the y dimension after launch is greater than just before landing.

True

Acceleration due to gravity only applies in the dimension.

Y

Neglecting air resistance, the velocity of a projectile in the x dimension is __.

Constant

If a ball has a velocity of 25 m/s in the y dimension when released, its velocity at the highest point is __.

0 m/s

If a ball has a velocity of 20 m/s in the x dimension, its velocity at the highest point is __.

20 m/s

If a ball has a velocity of 25 m/s in the y dimension when released, its velocity when returning to the same height is __.

−25 m/s

If a ball has a velocity of 20 m/s in the x dimension when released, its velocity when returning to the same height is __.

20 m/s

The angle of a projectile needed to achieve maximum height is __.

90 degrees

The angle of a projectile needed to achieve maximum distance is __.

45 degrees

A ball thrown vertically upward at 42 m/s is just above ground coming down. What is its velocity?

−40 m/s

If a ball is thrown vertically upward at 38 m/s, what maximum height is reached?

74 m

A ball thrown vertically upward has what acceleration at its maximum height?

−9.8 m/s²

Before reaching maximum height, what is true of velocity and acceleration?

Velocity upward, acceleration downward

A stone thrown downward at 10 m/s hits the water after 1.8 s. From what height was it thrown?

34 m

If a ball is thrown upward at 52 m/s, how much time until it reaches maximum height?

5.3 s

An object thrown upward at 25 m/s has what velocity after 3.0 seconds?

4 m/s downward

Ignoring air resistance, a horizontally fired Nerf dart has maximum velocity __.

Just before hitting the ground

Which of the following could cause positive horizontal acceleration?

An engine providing thrust

What is the biggest assumption when horizontal acceleration is zero?

Neglecting air resistance

The variable that always connects x and y motion is __.

Time

Acceleration is defined as the rate of change of __.

Velocity

The most common units for acceleration are __.

m/s²

(True or False) Negative acceleration always implies slowing down.

False

Positive acceleration with negative velocity means the object is __.

Slowing down and moving backward

(True or False) Rising objects come to a complete stop at the highest point.

True

(True or False) Acceleration is negative going up and positive going down.

False

(Test 2 Graphs) Which graph shows speeding up in the positive direction?

C

(Test 2 Graphs) Which graph shows slowing down in the positive direction?

A

(Test 2 Graphs) Which graph shows speeding up in the negative direction?

B

(Test 2 Graphs) Which graph shows slowing down in the negative direction?

D

(Test 2 Velocity Graph) Initial velocity from 0–4 s is __.

−10 m/s

(Test 2 Velocity Graph) Final velocity from 0–4 s is __.

10 m/s

(Test 2 Velocity Graph) Average velocity from 0–4 s is __.

0 m/s

(Test 2 Velocity Graph) Change in position from 0–4 s is __.

0 m

(Test 2 Velocity Graph) Acceleration from 0–4 s is __.

5 m/s²

When an object falls off a table, its initial downward velocity is __.

0 m/s

When an object is thrown downward, its initial velocity equals __.

The velocity at which it was thrown

When a ball is thrown upward at 20 m/s, its velocity when returning to the same height is __.

−20 m/s

(Test 2 Motion Graphs) Which graph shows an object not moving?

A

(Test 2 Motion Graphs) Which graph shows an object moving backward?

C

(Test 2 Motion Graphs) Which graphs show motion forward?

B, D, E

(Test 2 Motion Graphs) Which graph shows speeding up?

D

(Test 2 Motion Graphs) Which graph shows slowing down?

E

(True or False) Backward or downward motion is typically negative velocity.

True

(True or False) Slowing down usually means negative acceleration.

False

Vectors require both magnitude and __.

Direction

(True or False) Distance is a vector.

False

(True or False) Distance is path dependent.

True

(True or False) Displacement is a vector and not path dependent.

True

(True or False) The Greek symbol delta (Δ) signifies change.

True

(True or False) Delta is calculated as final minus initial.

True

(True or False) The standard unit for distance in physics is miles.

False

(True or False) Velocity is a vector.

True

(True or False) Average speed is displacement divided by time.

False

(True or False) Speed can never be negative.

True