fbpx

Kinetic energy – problems and solutions

Kinetic energy – problems and solutions

1. Two cars have the same mass, moving with different kinetic energy. The kinetic energy of the first car is 9 times the second car’s kinetic energy. The first car speed comparison with the second car is …..

Known :

Mass of car A (mA) = m

Mass of car B (mB) = m

The kinetic energy of car B (KEB) = KE

The kinetic energy of car A (KEA) = 9 KE

Wanted: The first car speed comparison with the second car

Solution :

The equation of kinetic energy :

KE = 1/2 m v2

2 KE = m v2

v2 = 2 KE / m

The speed of car A :

v2 = 2 KEA / mA = 2 (9 KE) / m = 18 KE / m

The speed of car B :

v2 = 2 KEB / mB = 2 KE / m = 2 KE / m

The comparison of the speed of car A and car B :

18 KE / m : 2 KE / m

18: 2

9 : 1 = 32 : 12

See also  Transformer and electric energy – problems and solutions

2. The kinetic energy of the object at point B = 100 J. If the mass of the object is 2.5 kg, then determine the kinetic energy of the object when it strikes the ground at point C. Acceleration due to gravity is 10 m/s2.

Solution

The kinetic energy of the object when it arrives at point B :Kinetic energy – problems and solutions 1

PE = m g h = (2.5)(10)(4) = 100 Joule

The kinetic energy of the object when it arrives at point C :

PE = m g h

PE = (2.5)(10)(4 + 6)

PE = (2.5)(10)(10)

PE = 250 Joule

See also  Equilibrium of the bodies on a inclined plane – application of the Newton's first law problems and solutions

Print Friendly, PDF & Email

Discover more from Physics

Subscribe now to keep reading and get access to the full archive.

Continue reading