3/11 Flashcards

1
Q

What is the formula to calculate Kinetic Energy (KE)?

A

KE = 1/2 m v²

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2
Q

What is the formula to calculate Potential Energy (PE)?

A

PE = mass × gravitational acceleration (9.8 m/s²) × height OR PE = Weight × Height

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3
Q

What units are used to measure Energy, Weight, Mass, Velocity, and Gravitational acceleration?

A

Energy = Joules
Weight = Newton
Mass = Kilograms
Velocity = m/s
Gravitational acceleration = 9.8 m/s²

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4
Q

A golf ball is struck with a mass of 2 kg. The ball leaves the club with a speed of 30 m/s. What is the ball’s energy?

A

KE = 1/2 × 2 kg × (30 m/s)² = 900 Joules

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5
Q

A ball is sitting at the top of a hill that is 21 m high. The ball weighs 15 N. What is the ball’s potential energy?

A

PE = Weight × Height = 15 N × 21 m = 315 Joules

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6
Q

A car is traveling with a velocity of 60 m/s and has a mass of 1200 kg. What is the car’s kinetic energy?

A

KE = 1/2 × 1200 kg × (60 m/s)² = 2,160,000 Joules

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7
Q

A golfer hits a golf ball with a mass of 1.3 kg. The ball leaves the club with a speed of 70 m/s. What is the ball’s kinetic energy?

A

KE = 1/2 × 1.3 kg × (70 m/s)² = 3185 Joules

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8
Q

A book is sitting on a bookshelf that is 20 m high. It weighs 8.5 N. What is the book’s potential energy?

A

PE = Weight × Height = 8.5 N × 20 m = 170 Joules

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9
Q

What is an example of Gravitational Potential Energy?

A

A rock sitting at the top of a hill has Gravitational Potential Energy.

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10
Q

What is an example of Elastic Potential Energy?

A

A stretched spring or rubber band has Elastic Potential Energy.

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11
Q

What is an example of Chemical Potential Energy?

A

A battery storing energy or food has Chemical Potential Energy.

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12
Q

What is an example of Magnetic Potential Energy?

A

A magnet held close to a metal object has Magnetic Potential Energy.

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13
Q

What is an example of Kinetic Energy?

A

A moving car or a person running has Kinetic Energy.

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14
Q

Where is there the most gravitational potential energy on a roller coaster? Why?

A

At the highest point of the track, because it has the greatest height relative to the ground.

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15
Q

Where is there the most kinetic energy on a roller coaster? Why?

A

At the lowest point of the track, because the car is moving at the greatest speed due to the conversion of potential energy into kinetic energy.

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16
Q

Would a roller coaster be able to make it to point 5 only by converting the gravitational potential energy from starting point 1? Explain.

A

No, because some energy is lost due to friction and air resistance, so the roller coaster would need an additional energy source to make it to point 5.

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17
Q

What is the law of conservation of energy? How does it relate to a roller coaster?

A

The law of conservation of energy states that energy cannot be created or destroyed, only converted from one form to another. In a roller coaster, gravitational potential energy is converted to kinetic energy, and vice versa, but the total energy remains constant (except for losses due to friction and air resistance).

18
Q

What is the formula for calculating the potential energy of an object at a height?

A

PE = mass × gravitational acceleration (9.8 m/s²) × height

19
Q

If a ball weighs 20 N and is lifted to a height of 10 meters, what is the potential energy of the ball?

A

PE = Weight × Height = 20 N × 10 m = 200 Joules

20
Q

A 5 kg object is moving with a speed of 10 m/s. What is its kinetic energy?

A

KE = 1/2 × 5 kg × (10 m/s)² = 250 Joules

21
Q

A car weighs 8000 N and is parked on a hill that is 15 meters high. What is the potential energy of the car?

A

PE = Weight × Height = 8000 N × 15 m = 120,000 Joules

22
Q

A 10 kg ball is dropped from a height of 50 meters. What is its gravitational potential energy just before it is released?

A

PE = mass × gravitational acceleration × height = 10 kg × 9.8 m/s² × 50 m = 4900 Joules

23
Q

What type of energy is associated with an object in motion?

A

Kinetic Energy

24
Q

A person stretches a spring by 0.5 meters. What type of energy does the spring store?

A

Elastic Potential Energy

25
Q

A chemical reaction occurs in a fuel cell that releases energy. What type of energy is released?

A

Chemical Potential Energy

26
Q

A car at the top of a hill has 6000 Joules of gravitational potential energy. As the car goes down the hill, the energy is converted into which type of energy?

A

Kinetic Energy

27
Q

What happens to the total energy of a system in a roller coaster ride as it goes up and down the track?

A

The total energy remains constant (conservation of energy), but it is constantly changing between potential and kinetic energy.

28
Q

Why is there less kinetic energy at the top of the hill on a roller coaster?

A

Because the car is moving slower due to having more potential energy at the higher point and less kinetic energy.

29
Q

What happens to a roller coaster car’s speed as it goes down a hill?

A

Its speed increases because gravitational potential energy is converted into kinetic energy.

30
Q

What is the relationship between height and potential energy?

A

The higher an object is, the greater its potential energy, since potential energy increases with height.

31
Q

If a 50 kg person is at the top of a 40 m high diving board, what is their potential energy?

A

PE = mass × gravitational acceleration × height = 50 kg × 9.8 m/s² × 40 m = 19,600 Joules

32
Q

When a rubber band is stretched, what kind of energy does it have?

A

Elastic Potential Energy

33
Q

How does a roller coaster demonstrate the conservation of energy?

A

The roller coaster converts gravitational potential energy into kinetic energy and vice versa, but the total energy (neglecting friction and air resistance) remains constant.

34
Q

What energy transformation occurs as a roller coaster car moves from the top of the hill to the bottom?

A

Gravitational potential energy is converted into kinetic energy.

35
Q

How does friction affect the energy of a roller coaster?

A

Friction causes the roller coaster to lose some energy, usually in the form of heat, which decreases its kinetic energy.

36
Q

What is the formula for calculating gravitational potential energy?

A

PE = mass × gravitational acceleration (9.8 m/s²) × height

37
Q

What type of energy is stored in a battery before it is used?

A

Chemical Potential Energy

38
Q

A moving car has 450,000 Joules of kinetic energy. If its mass is 1500 kg, what is its speed?

A

KE = 1/2 × m × v² → 450,000 J = 1/2 × 1500 kg × v² → v = √(2 × 450,000 / 1500) = 24.49 m/s

39
Q

What type of energy is stored in the fuel of a car before it is burned in the engine?

A

Chemical Potential Energy

40
Q

How does the speed of an object affect its kinetic energy?

A

Kinetic energy increases with the square of the object’s speed (KE = 1/2 m v²), so doubling the speed results in four times the kinetic energy.