Question

A bus and a car have the same momentum. If the kinetic energy of the bus is K1 and kinetic energy of car is K2 then
(a.).. K1=K2
(b) K1<K2
(c) K1>K2​

Answer 1

Answer:

b

Explanation:

KE = p/2m

so for same momentum heavier objects will have less kinetic energy

Answer 2

Answer:

Kinetic energy of a car is greater than the Kinetic energy of a bus

i.e., option (b) K1 < K2 is correct.

Explanation:

Here,

Mass of bus > Mass of car

Kinetic energy K,

$K =\frac{1}{2} mv {}^{2}$

where, m is mass and v is velocity.

If we multiply and divide the above equation with m then,

$K=\frac{1}{2} \times \frac{m}{m} \times mv {}^{2}$

So,

$K= \frac{1}{2} \times \frac{ {m}^{2} {v}^{2} }{m}$

But, P (momentum) = m (mass) × v (velocity)

So,

$P {}^{2} = {m}^{2} {v}^{2}$

So,

$K= \frac{p {}^{2} }{2m}$

But, here in question is given that the momentum of the car and bus is the same.

So, Kinetic energy is inversely proportional to the mass of the objects.

Mass of the bus is greater so its Kinetic energy which is given K1 must be low.

And mass of the car is lesser so its Kinetic energy which is given K2 must be high.

Hence, K1 < K2.

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