Question

The kinetic energy of a body is directly proportional
to the square of its speed when the mass is kept
constant and is directly proportional to mass when
its speed is kept constant. A body with a mass of
2 kg and a speed of 10 m/s has a kinetic energy of
100 joules. What is the kinetic energy of a body
whose mass is 20 kg and speed is 1 m/s?
(A) 100 joules
(B) 1000 joules
(C) 10 joules
(D) 20 joules

Answer 1

Answer: 10 joules

Step-by-step explanation:

K.E.∝(s)²m⇒ K.E.=k.(s)²m⇒ k=K.E./(s)²m

k= K.E.1 / ( (s1)² * m1) = K.E.2 / ( (s2)² * m2)

Hence, 100 / ( (10)² × 2) = K.E.2 / ( (1)² × 20)  

K.E. = 10 joules