a dish of mass 20g is kept horizontally in air by firing bullets of mass 10gm at the rate of 10 per sec. if the bullets rebounded with same speed ,what is the velocity with which the bullets are fired?
Answers
Answer:
The answer will be 0.95 m/s
Explanation:
According to the problem the mass of the dish is given and t is kept horizontally
and the mass of the bullets is also given which is 10 gm
the rate of firing the bullets is 10 /s
The downward force = mg = 20/1000 x 9.81 = 0.19N
Let the velocity of the bullet when it is fired u m/s
Therefore the momentum of the bullet is , 10 /1000 u = 0.01u kg m/s
Therefore the momentum of bullet after rebound = - 0.01u kg m/s
change in momentum = -0.01u-0.01u =-0.02u kg m/s
As the bullet is fire at rate of 10 /s
Therefore, 0.19 = 0.02u x 10
=> u = 0.95 m/s
Answer:98cm/s
Explanation force of bullet=Mass ×gram of dish
n=number of bullets
n(ma)=mg of dish
10(10×v-u/t)=mg
In rebounding the
"-"becomes"+"
So 10×10×v+v/t=20×10
10×10×10+v/10=200
V=200/100=2
V=100-2=98cm/s