Motion, Force, Work and Energy

If force and displacement of particle in the direction of the force are doubled. Work would be:

• Double

• 4 Times

• Half

• 1/4 Times

Burning of coal is an example of conversion of

• chemical energy to thermal energy
• mechanical energy to heat energy

• heat energy to light energy

• light energy to heat energy

the decrease in the potential energy to a ball of mass 20 kg which falls from a height of 50 cm ,is

• 100 J
• 98.1 J
• 49 J
• 75 J

a ball of mass 2 kg and another of mass 4 kg are dropped together form a 60 feet tall building. after a fall of 30 feet each towards earth, their respective kinetic energies will be in the ratio of

• 1 : 2
• 3 : 2
• 2 : 1
• 1 : 1

which is not a unit energy ?

• kilo watt hour

• watt
• calorie
• joule

work is said to be done when

• A force causes an object to move.
• An object is at rest.
• A force is applied without movement.
• Energy is transferred without displacement.

a fast wind can turn the blade of a windmill because it possess

• kinetic energy
• thermal energy
• potential energy
• gravitational force

when we compress a coil spring, we do work on it. the elastic potential energy

• increase

• decrease

• remains the same

• disappears

what is the work done by gravity on a man standing on a platform?

• 0 Joules
• positive

• negative

• depends on the situation

a body at rest can have

• speed

• energy

• momentum

• velocity