Energy Conservation

A 15.0-kilogram mass is moving at 7.50 meters per second on a horizontal, frictionless surface. What is the total work that must be done on the mass to increase its speed to 11.5 meters per second?

• 120. J

• 422 J

• 570 J

• 992 J

Tags

NGSS.HS-PS3-1

A child, starting from rest at the top of a playground slide, reaches a speed of 7.0 meters per second at the bottom of the slide. What is the vertical height of the slide? [Neglect friction.]

• 0.71 m

• 2.5 m

• 1.4 m

• 3.5 m

Tags

NGSS.HS-PS3-2

A small electric motor is used to lift a 0.50-kilogram mass at constant speed. If the mass is lifted a vertical distance of 1.5 meters in 5.0 seconds, the average power developed by the motor is

• 0.15 W

• 1.5 W

• 3.8 W

• 7.5 W

Tags

NGSS.HS-PS3-2

Two construction cranes are used to lift identical 1200-kilogram loads of bricks the same vertical distance. The first crane lifts the bricks in 20. seconds and the second crane lifts them in 40. seconds. Compared to the power developed by the first crane, the power developed by the second crane is

• the same

• twice as great

• half as great

• four times as great

A 1.47-newton baseball is dropped from a height of 10.0 meters and falls through the air to the ground. The kinetic energy of the ball is 12.0 joules the instant before the ball strikes the ground. The maximum amount of mechanical energy converted to internal energy during the fall is

• 2.7 J

• 12.0 J

• 14.7 J

• 26.7 J

After a 65-newton weight has fallen freely from rest a vertical distance of 5.3 meters, the kinetic energy of the weight is

• 12 J

• 340 J

• 910 J

• 1800 J

A garden tractor drags a plow with a force of 500 Newtons a distance of 10 meters in 20 seconds. How much work is done?

• 25 J

• 250 J

• 1000 J

• 5000 J

Tags

NGSS.HS-PS2-1

Which pair of quantities can be expressed using the same units?

• acceleration and weight

• impulse and potential energy

• power and momentum

• work and kinetic energy

A cart weighing 10 newtons is pushed 10 m on a level road by a force of 5 newtons.

What is the increase in its potential energy?

• 1 Joule

• 50 Joules

• 100 Joules

• 0 Joules

Tags

NGSS.MS-PS3-2

A student throws a ball upward at an angle of 45˚.

Which statement best describes the ball at the highest point it reaches?

• its acceleration is zero.

• its acceleration is at a maximum

• its potential energy is at a minimum

• its kinetic energy is at a minimum.

Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-2