A ball of mass 0.1 kg strikes a wall normally with a speed of ` 30 m s ^( - 1 ) ` and rebounds with a speed of ` 20 ms ^( - 1 ) `. The impulse of the force exerted by the wall on the ball is

Options

A. ` 1 N - s `
B. `5 N - s `
C. `2 N-s `
D. `3 N -s `

Answer

B

Explanation

Impulse = Change is momentum ` p _ i- P _ f `
direction of ` P _ f and p_i` apposite to each other.
` therefore ` Impulse = `m u - ( - mv ) `
` = m u + mv = m ( u + v ) = 0.1 ( 30 + 20 ) `
` = 0.1 xx 50 =5 N - s `