Title: Mid Unit Assessment
Course: MNPCC Physics > Section: Newton's Second Law

The assessment is designed to check for your understanding after completing some of the unit's activities.

Q: Car A is traveling down the road and goes from 30 to 35 m/s in 5 seconds.  During the same 5 seconds Car B goes from 45 to 35 m/s.  Which car accelerates the most?
- Car B (Correct.)
- Car A (The direction of the acceleration is different, B had a greater magnitude.)
- The accelerations are identical. (You have to look at more than just the final speed.)
A: Car B
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: Two cars are traveling down the road.  Car A travels for 10 seconds at 25 m/s and Car B accelerates uniformly from 20 to 28 m/s over 10 seconds.  Which car travels the furthest during this 10 second time interval?
- They cover the same distance. (Car A has a slightly faster average speed.)
- Car A travels further. (Correct.)
- Car B travels further. (Car A has a slightly faster average speed.)
A: Car A travels further.
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: A car accelerates from 30 to 10 m/s in 2 seconds.  What is the acceleration of the car?
- -10 m/s^2 (Correct.)
- 10 m/s^2 (You subtracted in the wrong direction.)
- 20 m/s^2 (You need to use the change in speed, not adding them up.)
- -20 m/s^2 (You need to use the change in speed, not the just adding them up.)
A: -10 m/s^2
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: A bike accelerates at 1 m/s^2 for 10 seconds.  If the bike started at 2 m/s, how far has it gone?
- 70 m (Correct.)
- 20 m (You cannot just use the initial speed.)
- 120 m (You can’t just use the final speed.)
- 50 m (You forgot it started at 2 m/s!)
A: 70 m
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: Which of the following best describes the motion that is depicted in the graph below?
- The object is speeding up in the negative direction. (Correct.)
- The object is slowing down in the positive direction. (The slope is increasing with time, positions also decreases, so you are exactly wrong.)
- The object is speeding up in the positive direction. (The position decreases with time, so it is going in the negative direction.)
- The object is slowing down in the negative direction. (The slope is increasing with time.)
A: The object is speeding up in the negative direction.
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: A 1000kg sphere and a 0.001kg sphere of the same size are dropped at the same moment from a very tall building, which best describes their motion?  Remember they are falling through the air and air resistance cannot be neglected.
- The 10000 kg will always be ahead of the other and reach the ground faster. (Correct.)
- Both will accelerate equally until reaching the ground at the same time. (This is only true if there were no air.)
- Both will accelerate equally at first, until the terminal velocity of the less massive one is reached, so the 10000 kg will hit the ground faster. (The more massive one will always have a greater acceleration in air.)
- Both will move at the same high constant speed, reaching the ground at the same time. (Under the influence of gravity and air, all objects will accelerate until reaching a terminal velocity.)
A: The 10000 kg will always be ahead of the other and reach the ground faster.
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: Two air hockey pucks are gliding across the table.  The force of friction/drag on each is roughly the same.  One puck is more massive than the other.  Which will come to a stop first?
- The less massive puck. (Correct.)
- The more massive puck. (Mass is inversely related to acceleration. This applies speeding up or slowing down.)
- They will stop in the same time. (Mass is related to acceleration.)
A: The less massive puck.
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: A car is traveling in the direction indicated by the green arrow.  If all of the red arrows indicate forces on the car, which option best describes the cars motion?
- The car is slowing down. (Correct.)
- The car is speeding up. (The forces are unbalanced in the direction opposite motion, so it is indeed slowing down.)
- The car’s speed is constant. (The forces are unbalanced in the direction opposite motion, so it is indeed slowing down.)
A: The car is slowing down.
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: A student is standing on a scale in an elevator and notices the scale reads more than what they weigh.  Which of the following diagrams correctly shows why this is?
A: (a choice with no text)
If wrong: The scale reads the upward normal force on the person, this would show a downward acceleration, and the scale reading under the person’s weight.
If wrong: If the scale was reading the person’s weight the forces would be balanced.
If right: Correct.
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: Two wheelbarrows have the same mass.  One is being pushed by a much stronger person.  Which wheelbarrow will accelerate the fastest?
- The one with more force. (Correct.)
- The one with less force. (Force is directly related to acceleration.)
- They will accelerate equally. (Force is related to acceleration.)
A: The one with more force.
If right: Your answer is correct.
If wrong: Your answer is incorrect.