Question

A ball rolls horizontally off a table of height 1.4 m with a speed of 4 m/s. How long does it take the ball to reach the ground?

Answer 1

As the ball rolls horizontally of a ta!ble (of height 1.4m) with a speed of `4"m/s"` ,the horizontal component of velocity will be `v_"hor"=(4cos0)"m/s"=4"m/s"` and vertical component will be `v_"ver"=(4cos90)=0"m/s"`

If the time required to reach the be t sec then by the equation of motion under gravity we can write

`h=u_"ver"xxt+1/2xxgxxt^2`

Taking `"acceleration due to gravity "`
`g=9.8"m/"s^2 and h=1.4m` we get

`=>1.4=0xxt+1/2xx9.8xxt^2`

`=>t=sqrt(2/7) s`