The Student Room Group

easy physics question

the speed of the ball just before hitting the floor for the first time is 4m/s. On bouncing, the ball loses half its kinetic energy. Show that the speed of the ball as it leaves the floor after the first bounce is 2.8m/s

ok we arnt given the mass of the ball

but wouldn't it just be 0.5[0.5(v^2)] as mass is a constant?

this gives v=0.25(4^2) =4... which is wrong??

how do i do this? so confused

thanks
Original post by Mr Tall
the speed of the ball just before hitting the floor for the first time is 4m/s. On bouncing, the ball loses half its kinetic energy. Show that the speed of the ball as it leaves the floor after the first bounce is 2.8m/s

ok we arnt given the mass of the ball

but wouldn't it just be 0.5[0.5(v^2)] as mass is a constant?

this gives v=0.25(4^2) =4... which is wrong??

how do i do this? so confused

thanks


If it loses half its ke after the bounce then
0.5mV220.5mV12=0.5\frac{0.5mV_2^2}{0.5mV_1^2} = 0.5

As you know V1 you can find V2

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