Question

find the momentum of a body of mass 100 g having a kinetic energy of 20J

Answer 1

1÷2×100÷1000×v×v=20
v×v=20×20
v=20
p=100÷1000×20
=2

Answer 2

Kinetic energy = 1/2 * mass * velocity ²,
Given that Kinetic energy = 20j,
mass = 100g = 0.1kg,

1 j = 1kg m²/s²,

Substitute those values in the first equation to get Velocity,

=> 20 = 1/2 * 0.1 * v²,
=> 40/0.1 = v²,
=> 400 = v²,
=> v = 20 m/s,

Now momentum = mass * velocity,
We already knew mass, and we also got velocity,

Substitute in them,
=> momentum = 0.1 kg * 20 m/s,
=> momentum (P) = 2 kgm/s,

Hope you understand,

Have a great day !!