MCQs for Work, Energy, and Power

A block of mass 5 kg slides down an incline of 30° from a height of 10 m. If friction is negligible, the speed of the block at the bottom is (g = 10 m/s²):

• 10 m/s

• 14 m/s

• 20 m/s

• 22 m/s

A particle is subjected to a force F=2i+3j and undergoes a displacement r=4i+5j. The work done by the force is:

• 23 J

• 26 J

• 28 J

• 35 J

A spring with spring constant 200 N/m is compressed by 0.1 m. The potential energy stored in the spring is:

• 1 J

• 0.5 J

• 2 J

• 10 J

A 2 kg object is moving at a speed of 10 m/s and comes to rest in 5 seconds due to a constant retarding force. The work done by the force is:

• -200 J

• -100 J

• 0 J

• 100 J

The efficiency of a machine is 80%, and it delivers 400 W of power. What is the input power?

• 500 W

• 320 W

• 800 W

• 480 W

A satellite of mass 500 kg moves in a circular orbit of radius 8000 km around the Earth. What is the total energy of the satellite? (Mass of Earth M=6×1024 kg, G=6.67×10-11 Nm2/kg2)

• -1.25 x 10¹¹ J

• -2.5 x 10¹¹ J

• -1.25 x 10¹⁰ J

• -2.5 x 10¹⁰ J

The work done by a force field F=k(xi+yj) in moving a particle from (0,0) to (1,1) is:

• k

• 2k

• 2k

• 0

Two bodies of masses m₁ and m₂ are moving with velocities v₁ and v₂ respectively. The ratio of their kinetic energies is given by:

• m₁v₁:m₂v₂

• m₁v₁²:m₂v₂²

• m₁²v₁:m₂²v₂

• m₁v₂:m₂v₁

The change in kinetic energy of a system when a constant force acts on it over a displacement d is given by:

• Fd

• 0.5Fd₂

• Fdcos⁡θ

• Fdsin⁡θ

A particle is moving in a straight line under the action of a variable force F=2x+3. What is the work done by the force in moving the particle from x=0 to x=4?

• 24 J

• 28 J

• 32 J

• 40 J