Answer:
7.5 kg
Explanation:
We are given that

Length of plank, l=3 m
Distance of fulcrum from one end of the plank=1 m

We have to find the mass must be on the other end if the plank remains balanced.
Let m be the mass must be on the other end if the plank remains balanced.
In balance condition






Hence, mass 7.5 kg must be on the other end if the plank remains balanced.
It was not the first time that a person who was in a few weeks ago, I
The amplitude of wave-c is 1 meter.
The speed of all of the waves is (12meters/2sec)= 6 m/s.
The period of wave-a is 1/2 second.
Answer:
The velocity of the man is 0.144 m/s
Explanation:
This is a case of conservation of momentum.
The momentum of the moving ball before it was caught must equal the momentum of the man and the ball after he catches the ball.
Mass of ball = 0.65 kg
Mass of the man = 54 kg
Velocity of the ball = 12.1 m/s
Before collision, momentum of the ball = mass x velocity
= 0.65 x 12.1 = 7.865 kg-m/s
After collision the momentum of the man and ball system is
(0.65 + 54)Vf = 54.65Vf
Where Vf is their final common velocity.
Equating the initial and final momentum,
7.865 = 54.65Vf
Vf = 7.865/54.65 = 0.144 m/s