DP014: C5 WORK AND ENERGY

The unit used to

measure work is the

• watt

• joule

• newton

• meter

1.     Calculate the work done at point O as shown in the FIGURE 1.

• – Fs cos θ

• Fs cos θ

• Fs sin θ

• • - Fs sin α

Which of the following is

the best example of work

being done?

• Pushing a stationary box

• Holding a box

• Lifting a box

• pulling a box with constant velocity

The gravitational

potential energy of an

object is due to

• its mass

• its acceleration due to gravity

• its height above the earth's surface

• all of the above

A ball is thrown upward with

some kinetic energy. What

happened to its kinetic energy at

the highest point?

• it's kinetic energy is lost

• it's all kinetic energy is absorbed by the air

• it's kinetic energy is converted to potential energy

• it's kinetic energy is remain same

Two ropes are attached to a box. Each rope is pulled with a force of 40 N at an angle of 35° to the direction of travel. The box is moved 20 m in the direction shown. Calculate the total work done. Ignore the friction.

• 655.32 J

• 1310.64 J       

• 458.86 J

• 917.72 J

FIGURE 2 shows an object of mass m passes a point X with a velocity of v. Then it slides up a frictionless incline plane and stops at point Y, height h above X. When a second object of mass  ½ m passes X with the velocity of ½ v , what height will it rise to?

• 1/4 h

• 1/2 h

• h

• 2h

Which point along the roller coaster has the greatest velocity?

• A

• B

• C

• D

A variable force is represented by a graph of F (Force) -x (displacement). Which one of the followings is the work done by this force?

• Slope of the curve

• Area bounded by the curve

• F value multiplied by t value

• F value divided by x value

Which one of the following situations will there be an increase in the kinetic energy?

• A satellite travels in a circular orbit around the Earth at a fixed altitude

• A box is pulled across a rough floor at constant speed

• A ball starts from rest and freely rolls downhill

• A projectile approach its maximum height