Physics Practice Tests – Work, Energy and Power (Questions with Answers and Explanations)

A bob of weight 0.1 N hangs from a massless string of length 50 cm. A variable horizontal force which increases from zero is applied to pull the bob until the string makes an angle of 60^o with the vertical. The work done is _____ (JAMB 2010)

A. 0.075 J   B. 0.025 J   C. 0.500 J    D. 0.250 J

An object of mass 20 kg is released from a height of 10 m above the ground level. The kinetic energy of the object just before it hits the ground is ____ [g = 10 ms^-2] (JAMB 2014)

A. 200 J   B. 4000 J   C. 2000 J   D. 500 J

A car travelling with a uniform velocity of 30 ms^-1 along a horizontal road overcomes a constant frictional force of 600 N. Calculate the power of the engine of the car. (WASSCE 2008)

A. 18 kW    B. 20 kW   C. 180 kW   D. 200 kW

An object is moving with a velocity of 5 ms^-1. At what height must a similar body be situated to have a potential energy equal in value with the kinetic energy of the moving body? (JAMB 2013)

A. 1.0 m   B. 25.0 m   C. 20.0 m   D. 1.3 m

An engine of a car of power 80 kW moves on a rough road with a velocity of 32 ms^-1. The force required to bring it to rest is ______ (WASSCE 2006)

A. 2.50 x 10⁶ N  
B. 2.50 x 10³ N  
C. 2.56 x 10⁶ N  
D. 2.80 x 10³ N