Name______Test A

Test 1: PHYSICS 103 Fall 2004

For all problems, assume that the magnitude of the acceleration of gravity is 10 m/s2

1)Erica lives 20 miles away. She told us in class that it takes her 20 minutes to commute to school each way every day. Her average speed during her trip is therefore:

  1. 60 miles per hour
  2. 30 miles per hour
  3. 1 miles per hour
  4. 1 km/hr
  5. None of these

2)A 10 kg ball is moving at a velocity of 120 m/s. If no forces act on the ball, the speed of the ball in 10 seconds will be:

  1. 200 m/s
  2. 20 m/s
  3. 120 m/s
  4. 0 m/s
  5. 140 m/s

3)The graph below plots Elena’s velocity verses time on her way to school yesterday. During which part of her trip is the magnitude of her acceleration the smallest?

  1. During the first 10 minutes (section A)
  2. From 10 to 30 minutes (section B)
  3. During the last 40 minutes of her trip (section C)
  4. Her acceleration is the same during the whole trip

4)As a ball freely falls, its

  1. acceleration increases
  2. velocity increases
  3. both of these
  4. none of these because gravity is not changing

5)Alexander kicks his physics book up in the air. In the absence of air resistance, the net force on the book at the top of its path after having been kicked is/are:

  1. the force due to the horizontal motion of the book
  2. the force due to gravity
  3. the force exerted by Alexander kicking and the force of gravity
  4. zero
  5. None of these

6)You and a large elephant jump off a high dive at the same time. The elephant weighs 100 times you do. Neglecting air resistance, who hits the water first?

  1. You
  2. The elephant
  3. You both hit the water at the same time
  4. Cannot be determined

7)Elise jumps off a cliff and lands in a lake 20 m below. Neglecting air resistance, the speed with which she hits the water is:

  1. 5 m/s
  2. 10 m/s
  3. 15 m/s
  4. 20 m/s

8)Disregarding air resistance, how fast must you toss a ball straight up in order for it to take 4 seconds to return to the level from which you tossed it?

  1. 5 m/s
  2. 7.5 m/s
  3. 10 m/s
  4. 15 m/s
  5. 20 m/s

9)An object is thrown horizontally off the top of a building with a velocity of 20 m/s and hits the ground 60 m away. How high up was the building? (Contributed by one of your fellow students. Great question, whoever you are)

  1. 20 m
  2. 60 m
  3. 45 m
  4. 10 m
  5. Cannot be determined

10)A 60 kg man is in an elevator that is accelerating downwards at the rate of 1.4 m/s2. What is the force exerted on the man’s feet by the floor of the elevator(contributed by one of your fellow students; excellent question!)

  1. 600 N
  2. 516 N
  3. 84 N
  4. 140 N
  5. 684 N

11)A car goes at a constant speed of 50 mph in a circle. Which of the following is true?

  1. The acceleration is zero
  2. The velocity is a constant
  3. The acceleration is nonzero
  4. The acceleration is changing

12)Ariel pushes a large elephant horizontally on a flat surface with a force of magnitude 200 N. The elephant moves with a constant forward acceleration. Which statement is most true about the magnitude of the force of kinetic friction acting on the elephant?

  1. It is greater than 200 N
  2. It is less than 200 N
  3. It is equal to 200 N
  4. None of the above are necessarily true

13)A ball is thrown off a cliff downwards at 5 m/s. Another ball is dropped off the same cliff at the exact same time. Neglecting air resistance, which of the following is true

  1. Both balls hit the ground at the same time since they both are acted upon by gravity
  2. Both balls hit the ground with the same speed
  3. Both balls have the same acceleration
  4. Cannot be determined

14)Two balls are rolled off a table at the same time, one with a speed of 10 m/s and the other with a speed of 50 m/s. Which of the following is true:

  1. The two balls hit the ground at the same time
  2. The ball with the greater speed reaches the ground first
  3. The ball with the greater speed will accelerate faster
  4. Both balls will reach the ground in 9.8 seconds

15)A girl is pushing a 10 kg block for 5 m along a rough surface with a constant horizontal force of 30 N. If the block is moving with an acceleration of 1 m/s2, which of the following is true :

  1. The net force on the block is 30 N
  2. The force of friction acting on the block is 20 N
  3. The velocity of the block is 3 m/s
  4. The force of friction acting on the block is 30 N
  5. The net force acting on the block must be zero

16)Michael pushes his 2 kg physics book along a table top, pushing it with a force of 10 N. If the book is greased so that friction is negligible, the book’s acceleration is?

  1. 0.2 m/s2
  2. 5 m/s2
  3. 20 m/s2
  4. 0

17)Chris jumps off a high dive. As he falls through the air, his acceleration:

  1. increases
  2. decreases
  3. is a constant equal to -9.8 m/s2
  4. 0

18)A 10 kg block with an initial velocity of 10 m/s slides 10 m across a horizontal surface and comes to rest. It takes the block 2 seconds to stop. The stopping force acting on the block is about?

  1. 5 N
  2. 10 N
  3. 25 N
  4. 50 N

19) A man and a woman are parachuting through the air from the same altitude with identical parachutes. If the man weighs twice as much as the woman, which one gets to the ground first?

  1. The man
  2. The woman
  3. both the same
  4. Cannot be determined.

20)Brad slowly lifts using rope a 1 kg box from the floor. Neglecting air resistance, if the rope exerts a force of 15 N upwards, how long will it take for the box to be raised to a height of 10 m (Contributed by one of your fellow students; great question)?

  1. 2 s
  2. 4 s
  3. 1.4 s
  4. 1 s
  5. Cannot be determined

21)You lift a 2 kg book up from the ground. If the book’s acceleration is 3 m/s2, the force you apply to the book is:

  1. Equal to its weight, approximately 20 N
  2. Aproximately 26 N upwards
  3. Approximately 14 N upwards
  4. zero
  5. Approximately 6 N upwards

22)Assume that two identical blocks with the same mass rest on the two inclines shown below. If the both blocks are at rest, which of the following can be concluded

  1. The force of friction between the block and incline A is greater than the frictional force between the block and incline B
  2. The frictional force is the same in both cases since the mass of the block is the same
  3. The net force on the block on incline A is greater than the net force on the block on incline B
  4. The net force on the block on incline B is greater than the net force on the block on incline A

Extra-Credit Challenge Problems (Contributed by your fellow students; these questions were excellent)

“It is not the answer that enlightens, but the question”

-Eugene Ionesco (1912 - 1994)

For all problems assume that the acceleration due to gravity is –10 m/s2.

1) A ball is thrown horizontally from the top of a 45m high building at 23 m/s; at the same time, another ball is thrown horizontally with a velocity of 13 m/s. How far apart from each other will the two balls land?

  1. 39 m
  2. 69 m
  3. 30 m
  4. 108 m
  5. Cannot be determined

2)A cannonball is positioned at the edge of a cliff 80 m high. If the cannon is positioned at an angle of 45 degrees above the ground and the initial velocity of the cannonball is 125 m/s, how far from the base of the cliff will the cannonball land?

  1. 80 m
  2. 120 m
  3. 483 m
  4. 354 m
  5. Cannot be determined

There was a mistake in this problem and none of the answers are correct (thanks to those who pointed it out); As a result of this typo, the test was out of 21 instead of 22 (I gave everyone an extra point).

Formulae:

average velocity = distance/time


For constant velocity: (here t is time and d is distance)

For constant acceleration: (here v is the change in velocity and t is time)

For anything moving at constant acceleration
, the position can be found using:

d = d0 + vo . t + ½ a.t2 where d is the final position after time t, d0 is the initial position, t is the time, a is the acceleration, and vo is the initial velocity

For anything moving at constant acceleration, the final velocity (v ) can be found using:

v= vo + a. t

From Newton’s second law:

F = m . a

Where F is the net force on the object, m is the mass and a is its acceleration. The units are Newtons if mass is in kg and a is in m/s2

A few math formulae and unit conversion factors:






Quadratic equation and solution