Question

A bird of mass 400 gm is flying horizontally at a certain height with constant accelerat ion of 5 m/s² The force exerted by surrounding air on the bird has magnitude ( g = 10m/s² )​

Answer 1

0.12s

0.08s

0.04s

12s

Answer :

A

Solution :

Velocity by which the ball hits the bat

v1=2gh1−−−−√=2×10×5−−−−−−−−−√ or v→1=+10m/s=10m/s .

Velocity of rebound

v2=2gh1−−−−√=2×10×20−−−−−−−−−√=20m/s or v→2=−20m/s .

F=mdvdt=m(v→2−v→1)dt=0.4(−20−10)dt=100N.

by solveing, dt=0.012 sec.