A 0.050 kilogram bullet is fired from a 4.0 kilogram rifle which is initially at
1 answer:
The recoil momentum of the rifle is (3) 20 kg-m/s
Explanation:
We can solve this problem by using the law of conservation of momentum. In fact, the total momentum of the bullet-rifle system must be conserved before and after the shot, in absence of external forces.
Before the shot, the total momentum of the system is zero, since both the bullet and the rifle are at rest:
(1)
After the shot, the total momentum of the system is:
(2)
where :
is the momentum of the bullet after the shot
is the recoil momentum of the rifle
Since momentum is conserved, (1) = (2):
Therefore we can find :
where the negative sign tells that the direction is opposite to the momentum of the bullet.
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Answer:
e. the air mattress exerts the same impulse, but a smaller net avg force, on the high-jumper than hard-ground.
Explanation:
This is according to the Newton's second law and energy conservation that the force exerted by the hard-ground is more than the force exerted by the mattress.
The hard ground stops the moving mass by its sudden reaction in the opposite direction of impact force whereas the mattress takes a longer time to stop the motion of same mass in a longer time leading to lesser average reaction force.
<u>Mathematical expression for the Newton's second law of motion is given as:</u>
............................................(1)
where:
dp = change in momentum
dt = time taken to change the momentum
We know, momentum:
Now, equation (1) becomes:
<em>∵mass is constant at speeds v << c (speed of light)</em>
and,
where: a = acceleration
also
so, more the time, lesser the force.
<em>& </em><u><em>Impulse:</em></u>
∵Initial velocity and final velocity(=0), of a certain mass is same irrespective of the stopping method.
So, the impulse in both the cases will be same.