Unit 2 Review: 2-D Motion

Vectors

100

What is another word for the "vector sum?"

Resultant

200

How do you "add" vectors when they are pointing in opposite directions?

Subtract

300

How do you "add" vectors when they are at right angles to each other?

Pythagorean theorem

400

Aaron and Collin are pulling on the hoverboard. Aaron is pulling with a force of 4 N and Collin is pulling with a force of 3 N. 1) What is the MAXIMUM possible net force that they exert on the hoverboard? 2) What is the MINIMUM possible net force that they exert on the hoverboard?

1) 7 N 2) 1 N

500

Aaron and Collin are pulling on the hoverboard. Aaron is pulling with a force of 4 N and Collin is pulling with a force of 3 N. Aaron is pulling upward and Collin is pulling to the left. What is the magnitude of their net force on the hoverboard?

5 N

Random Other Things

100

When an object is in static equilibrium, what is true about the net force on the object?

It is zero

200

1) Define "projectile." 2) Define "range." 3) At what angle does a projectile have its maximum range?

1) A launched object, only gravity acts on it 2) The horizontal distance traveled by an object 3) 45 degrees

300

Two marbles start from the same height. Ms. Johnson uses the launcher to shoot Marble A horizontally across the room, and Mike just drops Marble B. 1) Which marble hits the ground first? 2) Why?

1) Neither 2) Horizontal motion is independent of vertical motion

400

When an object is turning or moving in a circle, how does the direction of its ACCELERATION (and the net force causing that acceleration) compare to the direction of its VELOCITY? Draw a picture or explain in words.

Perpendicular

500

Why do you accelerate faster on a steep slide than a not-steep slide? List TWO reasons.

1) Friction is less 2) Motion is more in the direction that gravity is pulling

Circular Motion and Torque

100

What is torque?

A force that causes an object to spin or rotate (to have rotational acceleration)

200

1) What does torque depend on? 2) What are the units of torque?

1) Force and distance from axis of rotation 2) N-m

300

1) What is the name of any force that keeps an object moving in a circle? 2) What direction does this force point in?

1) Centripetal force 2) Towards the center of the circle

400

1) What does "period" mean in the context of uniform circular motion? 2) If you increase the period of a rotating object, how will that affect the SPEED at which it moves around the circle? (increase or decrease?)

1) How long it takes to complete one revolution 2) It will decrease

500

Can an object be accelerating if it is moving at a constant speed? Why or why not?

Yes because its direction can be changing

Projectile Motion

100

What does "trajectory" mean?

The path of a projectile through the air

200

Let's say an object is launched from a height of 1 m above the ground and lands (several meters away) at that same height above the ground. 1) How does the time that it took to go UP compare to the time it took to go DOWN? 2) Why?

1) They are the same 2) Symmetrical trajectory

300

Horizontal motion and vertical motion are independent. Let's consider the VERTICAL (up-down) motion of a projectile. 1) Is there a net force acting in this direction? If so, what is it? 2) What is its acceleration in this direction? 3) Does its velocity in this direction change?

1) Yes -- gravity 2) -9.8 m/s2 3) Yes

400

Horizontal motion and vertical motion are independent. Let's consider the HORIZONTAL (left-right) motion of a projectile. 1) Is there a net force acting in this direction? If so, what is it? 2) What is its acceleration in this direction? 3) Does its velocity in this direction change?

1) No 2) 0 m/s2 3) No

500

At what point in their trajectories would each of the following projectiles have zero VERTICAL velocity? 1) An object launched horizontally (at a launch angle of 0 degrees) 2) An object launched at an angle

1) Initially 2) At its peak

MATH!

100

Ms. Johnson is trying (and failing) to loosen a bolt on one of the refrigerators that she used to rip apart at her old job. She pushes on the 1.5 m long wrench (yes, it’s huge) with a force of 300 N. How much torque does she exert on the bolt?

450 N-m

200

Ms. Johnson is swinging her boyfriend’s cat, Richard, around in a circle. She’s holding Richard 0.3 m away from her body and it takes 1.2 seconds for her to make a complete circle. What is the speed of Richard’s rotation around Ms. Johnson?

1.57 m/s

300

Ms. Johnson is standing on her 1.0 m high desk and kicks her Term 1 gradebook into the air. It flies through the air for 2.5 seconds and lands on the ground 9.5 m away from her. What is her book's initial HORIZONTAL velocity?

3.8 m/s

400

Richard the cat is being swung around in a circle at a speed of 1.57 m/s. He has a mass of 11 kg and is being held 0.3 m away from Ms. Johnson's body. What is the centripetal force keeping him in this circle?

90.4 N

500

Ms. Johnson is standing on her 1.0 m high desk and kicks her Term 1 gradebook into the air. It flies through the air for 2.5 seconds and lands on the ground 9.5 m away from her. What is her book's initial VERTICAL velocity?

11.85 m/s