Physics Final Exam Review

Scalar & Vector

100

What quantities only have magnitude?

Scalar quantities

200

What quantities have both magnitude and direction?

Vector quantities

300

Is speed a scalar or vector? Is velocity a scalar or vector?

Speed = scalar (NO direction)

velocity = vector (includes direction)

400

On a morning walk, you walk 5 meters north, stop, then walk another 10 meters north. Then, you turn to walk 7 meters south, stop, and walk another 8 meters south. How does your total distance compare to your total displacement?

distance = 5 + 10 + 7 + 8 = 30 meters

displacement 5 + 10 + (-7) + (-8) = 0 meters

500

In the city in order to catch the subway, you have to walk 3 meters East  and then 4 meters North. What is your total displacement?

displacement = A² + B² = C²

displacement = 3² + 4² = 

displacement = 5 meters, NE

Motion

100

When you run laps around a track, how does your distance compare to your displacement?

After every lap your distance increases but your displacement remains zero because you keep returning to your starting position after each lap. 

200

Describe a scenario where your speed remains constant but your velocity is constantly changing?

When your SH/TL van drives around the curves of a roundabout because their speed remains the same but their direction is constantly changing. 

300

For each scenario below, sketch a distance-time graph that shows that motion. 

#1-at rest

#2-positive, constant speed

#3-accelerating

#4-decelerating

See the board for examples

400

A car accelerates at a rate of 3.0 m/s². If its original speed is 4.0 m/s, how many seconds will it take the car to reach a final speed of 25.0 m/s?

Use kinematics equation #3

t = (v_f - v_i) / a

t = (25-4)/3 = 7 s

500

A baseball is hit straight up in the air and takes 2 seconds to reach a maximum height of 12 meters. What was the speed of the baseball when it left the bat?

Use Kinematics Equation #6

x = (1/2) (v_i + v_f) t   and solve for v_i

v_i = 12 m/s

Forces

100

What are Newton's 3 Laws of Motion?

1st Law = at rest, stay at rest OR in motion, stay in motion

2nd Law = F=ma

3rd Law = every action has an equal and opposite reaction

200

Identify the reaction to each:

#1-Hand punches wall with 50 N

#2- Car tire pushes backwards on the road

#3- Earth pulls down on a person with 150 N

#1-Wall hits hand with 50 N

#2-Road pushes car tire forward

#3-Person pulls up on the Earth with 150 N

300

My heavy, riding lawn mower ran out of gas and I had to push it back into my shed. Why was it easier to push the mower once it was already moving as compared to when it was at rest?

From Newton's 1st Law, it's easier to keep an object in motion as compared to getting an object into motion because you have to overcome inertia to get it moving. 

400

You push a heavy box of 150 kg with 650 N to the right while the floor applies 500 N of friction to the left. 

#1-Draw a Free-Body-Diagram of the problem

#2-What is the Net Force acting on the box?

#3-What is the acceleration of the box?

#1-See the board

#2- Net force = 650 + (-500) = 150 N, right

#3- Net Force = ma 

a = 1 m/s²

500

A 60 kg person stands on a scale in an elevator that is accelerating downwards at 1 m/s². Use g =10 m/s² , 

#1-What is the weight of person?

#2- Does the scale read the same, more, or less than the person's weight?

#3-How much does the scale exactly read?

#1- Weight = mg = (60)(10)= 600 N

#2-Scale should read less because it's accelerating downwards 

#3- Weight - F_normal = (m)(a)

600 - F_normal = (60)(-1)

F_normal = 540 N

Gravity & Kepler

100

How is mass of two objects related to the force of gravity between them?

Directly related

200

How is distance between two objects related to the force of gravity between them?

Inverse square

300

If the mass of one object is quadrupled, what happens to the force of gravity?

Because mass is directly related to the force of gravity, the force of gravity will also be quadrupled.

400

If the force of gravity is 20 N, what would the new force of gravity be if the mass of one object doubled and the mass of the other object tripled?

F_g = (2x)(3x) = 6x F_g = 6x20 N=120 N

500

If the force of gravity is 20 N, what would the new force of gravity be if the mass of both objects is doubled while the distance between them also doubled?

F_g = (2x)(2x)/(2²) = 1x F_g = 20 N

Energy

100

What is potential energy?

Stored energy

200

What does kinetic energy depend on?

mass and speed (squared)

300

Why is the first hill on a roller coaster always the tallest? 

The first hill has to be the tallest in order to give the roller coaster enough energy to get through it. If any hills after it were taller, then the roller coaster wouldn't have enough energy to get up it. 

400

See the board for the roller coaster track. 

Rank the potential and kinetic energy from greatest to least.

Potential Energy = A, C, B = D

Kinetic Energy = B = D, C, A

500

See the board for the roller coaster track. Use g = 10 m/s²  and mass is 10 kg and the first hill is 10 meters high. 

How fast is the roller coaster traveling at Point B?

See board for answer.