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

This pre-test will be used to determine what you know about 2D motion going into the unit.

Q: If a student walks 3 km north and 4 km west, what is their total displacement?
- 5 km northwest (correct)
- 7 km northwest (incorrect magnitude.)
- 7 km southeast (incorrect magnitude and direction)
- 5 km southeast (incorrect direction.)
A: 5 km northwest
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 (Correct)
- 5 N up and 8.7 N to the right (you have the magnitudes switched around)
- 8.7 N down and 5 N left (you have the directions reversed)
- 5 N down and 8.7 N left (you have everything all switched around.)
A: 8.7 N up and 5 N to the right
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: Three sailboats are going across the river.  Each is going at a different angle, but their speeds are such that the component of their speeds to the right are identical.  Which boat will get across the river first?
- All will arrive at the same time. (Correct)
- Boat A (A will travel the least down stream, but they will all make landfall at the same time.)
- Boat B (B will travel the a bit more than A and less than C down stream, but they will all make landfall at the same time.)
- Boat C (C will travel the most down stream, but they will all make landfall at the same time.)
A: All will arrive at the same time.
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: When a ball is thrown through the air, what would best describe its motion in the horizontal and vertical directions?
- Horizontal is a constant speed and vertical is a constant acceleration. (Correct.)
- Horizontal is a constant acceleration and vertical is a constant speed. (The only unbalanced force is in the vertical direction.)
- Constant speed in both the horizontal and vertical directions. (There is a force in the vertical direction.)
- Constant acceleration in both the horizontal and vertical directions. (The only force is in the vertical direction.)
A: Horizontal is a constant speed and vertical is a constant acceleration.
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: If you drop a marble from 4.0 m above the ground how long will it take to hit the ground?  Remember the acceleration due to gravity is 9.8 m/s^2.
- 0.90 seconds (Correct)
- 0.82 seconds (You solved for the square of time.)
- 0.41 seconds (The 9.8 m/s/s is an acceleration not a speed.)
A: 0.90 seconds
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: A ball attached to a string is being swung around in a circle.  In what direction is the force on the ball at the moment shown here that keeps it moving in a circular path?
- D (Correct)
- B (It feels as if that is the direction of the force because of inertia.)
- A (Not sure why you would think that.)
- C (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: D
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: A car is going around a corner and hits a patch of ice which for the sake of this question has absolutely no friction, which direction will the car move while on the ice.
- B (Correct)
- A (There is no force in that direction and that requires a change in motion to do that.)
- C (There is no force in that direction and that requires a change in motion to do that.)
A: B
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: How is the force that causes you to turn related to the speed and radius of the turn?
- Directly related to the speed, inversely related to the radius. (Correct.)
- Directly related to both the speed and the radius. (Bigger radii requires less force.)
- Inversely related to both speed and the radius. (More speed requires more force.)
- Directly related to the radius, inversely related to the speed. (This is backwards.)
A: Directly related to the speed, inversely related to the radius.
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: How does the force of gravity on a person vary with their distance from the center of the Earth?
- The force decreases as you get further away but is present out into space. (Correct.)
- The force decreases as you get further away, ceasing once you are in space. (How would things stay in orbit then?)
- The force remains constant within the atmosphere, and ceases in space. (The atmosphere has nothing to do with it.)
- The force remains constant as long as you are turning with the Earth. (The force has nothing to do with rotation.)
A: The force decreases as you get further away but is present out into space.
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: If you doubled the mass of the Earth and doubled your own mass, what would happen to your weight?
- Your weight would increase four times. (Correct.)
- Your weight would increase two times. (Your weight is affected by both masses.)
- Your weight would remain the same. (So your weight stays the same when you eat a lot of food?)
A: Your weight would increase four times.
If right: Your answer is correct.
If wrong: Your answer is incorrect.