Physics Energy

Person 1 pushes half as hard against a stationary brick wall as Person 2. Which of the following statements is correct?

• Both do positive work, but person 2 does four times the work of person 1

• Both do positive work, but person 1 does twice the work of person 2.

• Both do the same amount of positive work

• Both do zero work

A 1.65 kg brick falls to the ground from a 9.0 m high roof. What is the approximate kinetic energy of the brick just before it touches the ground?

• 148.5 J

• 8.25 J

• 66.83 J

• 82.5

Tags

NGSS.HS-PS3-1

John pushes his little sister on her sled with a force of 700 N and does 145,000 J of work. How far did she push him?

• 207 m

• 4.8 m

• 1015 m

• 20.7 m

Tags

NGSS.MS-PS2-2

NGSS.MS-PS3-4

A 100 kg man and a 50 kg boy are jogging at the same speed. Which statement is true about the kinetic energies of the man and boy?

• KE of the man = 2 KE of the boy

• KE of the man = ½ KE of the boy

• KE of the man = 4 KE of the boy

• KE of the man = ¼ KE of the boy

A snowboarder with a mass of 80 kg is riding on a half-pipe with a maximum height of 4.8 meters. What is his maximum velocity at the bottom of the half-pipe?

• 9.8 m/s

• 3840 m/s

• 96 m/s

• 13.8 m/s

Tags

NGSS.HS-PS3-1

How can the amount of power required to move an object can be increased without changing the amount of work required?

• Decrease the time required to do the work.

• Increase the time required to do the work.

• Increase the friction on the surface over which the object is moving.

• Increase the weight of the object being moved.

A toy car with a mass of 2.1 kg is rolling on a table at a velocity of 2 m/s. If the gravitational potential energy of the car is 80 J, what is its mechanical energy?

• 84.2 J

• 4.2 J

• 75.8 J

• 88.4 J

Tags

NGSS.HS-PS3-1

A weightlifter raises a 75 N weight from the ground to a height of 1.5 meters in 30 seconds. What was the power spent by the weightlifter?

• 3.75 W

• 112.5 W

• 50 W

• 45 W

Which object has the greatest gravitational potential energy?

• 1.8 kg mass at a height of 50 m

• 3.1 kg mass at a height of 24 m

• 2.6 kg mass at a height of 27 m

• 4.2 kg mass at a height of 29 m

Tags

NGSS.HS-PS2-4

A toy helicopter with a mass of 2 kg is flying 1 meter above the ground at 2 m/s. The helicopter increases its height to 2.5 meters above the ground. What is the change in energy of the system?

• 30 J

• 300 J

• 50 J

• 500 J

Tags

NGSS.HS-PS3-1