Question

Please solve q 12?

Answer 1

P

Explanation:

`m_P = 1/2m_Q` and `v_P=2v_Q`, so that the kinetic energies are related by

`K_P = 1/2 m_P v_P^2 = 1/2 (1/2m_Q)(2v_Q)^2 = 2 K_Q`

Assuming both bullets face the same retarding force, P will penetrate twice as much (the work done by the retarding force in both cases must be the initial kinetic energy of the bullet)

Answer 2

The answer is `"option (a)"`

Explanation:

The momentums of the bullets are the same

`m_Pv_P=0.010*20=0.2kgms^-1`

`m_Qv_Q=0.020*10=0.2kgms^-1`

But the kinetic energies are

`KE_P=1/2m_Pv_P^2=1/2*0.010*20^2=2J`

`KE_Q=1/2m_Qv_Q^2=1/2*0.020*10^2=1J`

Therefore,

`KE_P>KE_Q`

As the kinetic energy of `P` is greater, the bullet `P` will pierce a distance hole in the target.

The answer is `"option (a)"`