MCAT RT Work, Power & Energy 2022

A body moves at a distance of 10 m along the horizontal by a force of 5N. if the work done is 25 J, then the angle between them is

• 0^o

• 30^o

• 60^o

• 90^o

  Work is always done on a body when

• A force acts on it

• It moves through a distance

• Its momentum changes

• It experiences and increases in energy through a mechanical influence.

A body is lifted by a man to a height of 1 m in 30s. Another man lifts the same mass to the same height in 60s. The work done by them are in the ratio

• 1 : 2

• 1 : 1

• 2 : 1

• 4 : 1

The time taken by an engine of power 10 kW to lift a mass of 200 kg to a height of 40 m is ( g = 10 m/s² )

• 2 s

• 4 s

• 8 s

• 16 s

What is the P.E lost by a stone of mass 1- kg when dropped from a 10 m high building

• Zero

• 98 Joules

• 100 Joules

• 980 Joules

The fossil fuels are mainly

• Coal and wood

• Petroleum and natural gas

• Both A & B

• None of these

If a bomb dropped from an airplane explodes in mid air

• Its KE increases

• Its total energy increases

• Its total energy decreases

• Its total momentum decreases

If the force acting on a body is inversely proportional to its speed, the kinetic energy of the body is

• Constant

• Directly proportional to time

• Inversely proportional to time

• Directly proportional to the square of time

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

• 968 J

• 9800 J

• 1980 J

• None of these

Work done will be positive (maximum) if the angle between force and displacement is

• 0^o

• 45^o

• 90^o

• 180^o