Question

42. A motor car of mass 800 kg has kinetic energy 40,000 Joules. The velocity of the
car is :​

Answer 1

Answer:

Step-by-step explanation:

Ek = ½mv2 ⇒ E = ½ 800 × 102 ⇒ E = 40,000 J Source:

Answer 2

Answer:

± 10 m / sec

Step-by-step explanation:

Given :

Mass of car = 800 kg

Kinetic energy = 40,000 J

We are asked to find velocity :

We have :

K.E. = 1 / 2 m v²

Putting value here :

40,000 = 1 / 2 × 800 × v²

40,000 = 400 v²

v² = 100

v = ± 10 m / sec

Therefore , velocity of car is ± 10 m / sec.