Title: Mid-Unit Assessment
Course: MNPCC Physics > Section: Two Dimensional Motion Unit

This assessment will check your understanding of the content that you have learned in this unit.

Q: Fill in the blanks:

As you increase your speed around the corner the centripetal force on you ________.  As you increase the radius of the turn the centripetal force on you ________.
- increases, decreases (Correct.)
- increases, increases (Bigger radii requires less force.)
- decreases, decreases (More speed requires more force.)
- decreases, increases (This is backwards.)
A: increases, decreases
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: A child is hanging on to a merry-go-round, which direction will the child fly off if she lets go at the moment depicted here?
- Down (Correct)
- Toward the center of the merry-go-round (There is no force in that direction and that requires a change in motion to do that.)
- Away from the center of the merry-go-round (There is no force in that direction and that requires a change in motion to do that.)
A: Down
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: What two component vectors could the vector shown here be broken into?
- 8.7 N up and 5 N to the right (You have the magnitudes switched around.)
- 5 N up and 8.7 N to the right (correct.)
- 8.7 N down and 5 N left (you have everything switched around)
- 5 N down and 8.7 N left (you have the directions backwards.)
A: 5 N up and 8.7 N to the right
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: What happens to the force of gravity as the distance between objects is doubled?
- The force is reduced by a factor of four. (Correct.)
- The force is reduced by a factor of two. (It is an inverse square relationship.)
- The force is increased by a factor of four. (Force decreases with distance.)
- The force increases by a factor of two. (Force decreases with distance.)
A: The force is reduced by a factor of four.
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: What would happen if both your mass and the mass of the Earth were cut in half?
- Your weight would increase four times. (weight is directly related to both masses.)
- Your weight would increase two times. (Weight is directly related to mass.)
- Your weight would remain the same. (So your weight stays the same when you remove clothing?)
- Your weight would decrease by a factor of two. (Both masses affect your weight.)
- Your weight would decrease by a factor of four. (Correct)
A: Your weight would decrease by a factor of four.
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: Two balls are thrown at 30 m/s.  One at 30 degrees off the horizontal, and one at 60 degrees off the horizontal.  What can be said of the two balls paths?
- They will have the same range but one will go higher than the other. (Correct.)
- The 30 degree pitch will go further as it travels faster down field. (It does go faster down field, but it is in the air less time.)
- The 60 degree pitch will go further as it is in the air for longer. (It is in the air longer, but it goes slower down field.)
A: They will have the same range but one will go higher than the other.
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: Three balls are being rolled off the table all at different speeds.  If they were all to leave the table at the same time which one will hit the ground first?
- All will hit at the same time. (Correct)
- Ball A (A will land furthest from the table but won't be in the air any longer.)
- Ball B (B will travel the a bit less than A and more than C down stream, but they will hit the ground at the same time.)
- Ball C (C will travel the least from the table, but they will all hit the ground at the same time.)
A: All will hit at the same time.
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: If you throw a ball horizontally at 10. m/s from 1.5 m above the ground, how far will it go before hitting the ground?
- 2.0 m (Correct)
- 1.5 m (9.8 is an acceleration not a velocity.)
- 15 m (It is more complicated than just multiplying the numbers together.)
- 3.1 m (you forgot that time squared is in the formula)
A: 2.0 m
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: A roller coaster is coming through the top of a loop.  In what direction is the force that is at that moment causing it to move around in a circle for the middle car (the one directly at the top)?

Photo by Coasterman1234 / CC-SA-BY 3.0
- Directly down. (Correct)
- Directly up. (It feels as if that is the direction of the force because of inertia.)
- To the right. (Not sure why you would think that.)
- To the left. (That is the direction the ball is moving, but that is not the direction of a force that would cause it to deviate from that path.)
A: Directly down.
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: A block of wood has a 6 N forward force on it, and an 8 N force to the left.  What is the unbalanced force on the block of wood?
- 10 N to the left of forward. (Correct)
- 14 N to the left of forward. (You have the direction correct but not the magnitude.)
- 14 N to the right of forward. (wrong magnitude and the opposite direction. (add head to tail))
- 10 N to the right of forward (You need to add head to tail.)
A: 10 N to the left of forward.
If right: Your answer is correct.
If wrong: Your answer is incorrect.