1.

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

Answer» Correct Answer - B
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 `


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