Irene Hernandez, Andres Noguera, Andres Robalino - Gravitational Motion, Rotational Motion, Work, Energy.

Question 1

What is motion?(Remember)

Answer 1

change with time of the position or orientation of a body

Question 2

What is the definition of work?

Remember

Answer 2

Work is equal to the product of the magnitude of the force and magnitude of displacement times the cosine of the angle between them.

Question 3

What is energy? (Remember)

Answer 3

What is the ability of an object to produce a change in itself or the world around it.

Question 4

What is gravitational motion?(Remember)

Answer 4

The force of attraction that bodies exert on one another as a result of their mass.

Question 5

What is rotational motion (Remember)

Answer 5

the motion of an object around a circular path, in a fixed orbit. Ceiling fan rotation

Question 6

What is power? (Identify)

Answer 6

It is the rate at which energy is transformed.

Question 7

The equation for work (Identify)

Answer 7

work = force x displacement

Question 8

What is the equation of speed in gravitation? (Identify)

Answer 8

The acceleration of gravity near the earth is g = -9.81 m/s^2. To find out something’s speed after a certain amount of time, you just multiply the acceleration of gravity by the amount of time since it was let go of.

Question 9

What is the equation to find kinetic energy?

Identify

Answer 9

KE = 0.5 * m * v²….. where: m - mass, v - velocity.

Question 10

What is the equation for rotational motion?(identify)

Answer 10

ω ¯ = ω 0 + ω 2 and v ¯ = v 0 + v 2 .

Question 11

A ball of mass 50 g is dropped from a height of 20 m.A boy on the ground hits the ball vertically upwards with a bat with an average force of 200 N, so that it attains a vertical height of 45 m. The time for which the ball remains in contact with the bat is [Take g= 10 m/s^2] (Calculation Questions)

Answer 11

1/80 of second

Procedure: attached

Question 12

What is the acceleration due to gravity on the surface of the Moon? (Calculation Questions)

Answer 12

1.62/s^2 ;

Question 13

A Golfer standing on the ground hits a ball with velocity of 52m/s at an angle θ above the horizontal. If tan θ= 5/12, the time for which, the ball is at least 15m above the ground is. (Calculation Questions)

Answer 13

2 seconds

Procedure: Attached

Question 14

On the surface of Mars? The mass of Mars is 6.418×102^3kg and its radius is 3.38×106m (Calculation Questions)

Answer 14

3.75m/s^2

Question 15

Two stones are projected with the same speed but making different angles with the horizontal. Their horizontal ranges are equal. The angle of projection of one is π/3, and the maximum height reached by it is 102m. Then the maximum height reached by the other is: (Calculation Questions)

Answer 15

34 m

Procedure: attached

Question 16

At what point does the skater have the most kinetic energy?

Answer 16

The skater has the highest amount of kinetic energy when he reaches the lowest point of the track.

Question 17

Where in the skatepark are potential and kinetic energy of the skater roughly equal?

Answer 17

The skater’s kinetic energy is at it’s highest at the bottom of the ramp, as none of it has been used it. Potential energy was being used to get the skater to the bottom if the ramp. The skater’s potential energy has been depleted at the bottom of the ramp, and is converted to kinetic energy.

Question 18

What happens to the potential and kinetic energy of a skater when there is friction?

Answer 18

As the skateboarder goes down the ramp, potential energy is converted to kinetic energy. Because of friction, some of the energy in the system is converted to heat energy. Once the kinetic energy is converted to heat, the energy cannot be converted back to the potential or kinetic energy in the system.

Question 19

What is the skaters speed when the skater is at the bottom of the track?

Answer 19

The speed is higher, but less than twice as fast.

Question 20

What type of energy does the skater have when they are in the middle of the track?

Answer 20

Potential Energy

Question 21

When would the skateboarder have the most potential energy?

Answer 21

the skater has the most potential energy at the top of the slope. As the skater moves down the slope, his potential energy decreases as the kinetic energy increases.

Question 22

What are some examples of gravitational force?

Answer 22

Stability of the Objects, Pouring Drinks, Rolling Objects, and, Fruits falling from trees.

Question 23

What are some examples of rotational motion?

Answer 23

Rotation of Earth, Fan Blades, Wheels of a Moving Vehicle, and Helicopter Rotor Blades

Question 24

What are the types of rotational motion?

Answer 24

• Rotation about a fixed axis
• Rotation about an axis of rotation
• Rotation about an axis in the rotation

Question 25

Which law can be used for rotational motion?

Answer 25

Newton’s second law for rotation and tells us how to relate torque, moment of inertia, and rotational kinematics.

Question 26

A skier starts at the top of a hill with 350J of energy. Assuming energy is conserved, what is her final kinetic energy?

Answer 26

350J

Question 27

A skier starts at the top of a hill with 100 J of potential energy. At the bottom of the hill, she has only 75 J of kinetic energy. Assuming that at the top of the hill she has only potential energy and at the bottom she has only kinetic energy, what can we conclude?

Answer 27

Work must have been done

Question 28

A rock is dropped in freefall from some initial height h. Which of the following describes its final velocity right before it hits the ground?

Answer 28

√ 2gh

Question 29

A 3.23kg book falls off the top of a 3.01m bookshelf. What is its kinetic energy right before it hits the ground?

Answer 29

95.28J

Question 30

A skier waits at the top of a 11.7m hill. He then skis down the slope at an angle of 27o above horizontal. What will his velocity be at the bottom of the hill?

Answer 30

15.14 m/s