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

This assessment will check the level of your skills now that you have completed all the required activities.

Q: Fill in the blanks:

When the speed of an object traveling around in a circle doubles, the centripetal force ______.  When the radius of an object traveling around in a circle doubles, the centripetal force ______.
- goes up four times, is cut in half (Correct.)
- goes up four times, is doubled. (Bigger radii requires less force.)
- is cut by a factor of four, is cut in half (More speed requires more force.)
- is cut by a factor of four, is doubled. (This is backwards.)
A: goes up four times, is cut in half
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: If one of the speed skaters falls, in which direction will he move?

Photo by jonthescone / CC-BY 2.0
- Towards the observer but slightly left. (Correct)
- Hard left, away from the center of the turn. (There is no force in that direction and that requires a change in motion to do that.)
- Hard right, towards the center of the turn. (There is no force in that direction and that requires a change in motion to do that.)
A: Towards the observer but slightly left.
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?
- 96.6 N up and 25.9 N left (Correct)
- 25.9 N up and 96.6 N left (you have the magnitudes switched around)
- 96.6 N down and 25.9 N right (you have the directions reversed)
- 25.9 N down and 96.6 N right (you have everything all switched around.)
A: 96.6 N up and 25.9 N left
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: Two balls are pitched at 15 m/s, one at 20 degrees and one at 60 degrees.  Which one will travel the furthest.
- The 60 degree ball. (Correct.)
- The 20 degree ball. (It travels faster down field but it isn't in the air long enough to go as far as the 60 degree ball.)
- Both will go the same distance. (This would only be true if they were complimentary angles.)
A: The 60 degree ball.
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: Three cannon balls are shot into the air so that the vertical component of their speeds are all the same, but their overall speeds are different.  Which cannonball will be in the air the longest?
- All will be in the air the same amount of time. (Correct)
- Ball A (A will travel the quickly down field, but they will all still be in the air the same amount of time.)
- Ball B (B will travel the somewhat quickly down field, but they will all still be in the air the same amount of time.)
- Ball C (C will not travel at all downfield, but they will all still be in the air the same amount of time.)
A: All will be in the air the same amount of time.
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: In which direction would the centripetal force on the child at the right of this image need to be in order to make him move in a clockwise fashion?

Photo by Saberwyn / CC-BY-SA 3.0
- To the left. (Correct)
- To the right. (It feels as if that is the direction of the force because of inertia.)
- Toward the top of the image. (Not sure why you would think that.)
- Toward the bottom of the image. (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: To the left.
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: A block of wood has a 1 N downward force of gravity, and a 4 N applied force to the left, what is the total force on the block?
- 4 N down and to the left (with proper significant figures) (correct)
- 5 N down and to the left (with proper significant figures) (incorrect magnitude.)
- 5 N down and to the right (with proper significant figures) (incorrect magnitude and direction)
- 4 N down and to the right (with proper significant figures) (incorrect direction.)
A: 4 N down and to the left (with proper significant figures)
If right: Your answer is correct.
If wrong: Your answer is incorrect.