Question

Question #8f009

Answer 1

Answer 2

We need to find R which is given by R=`U_x`T

However, we need to find time of flight, T.

Using constant acceleration linear equations;

`g=(V_y-U_y)/T` and `h_y=((U_y+V_y)/2)T`
Substitute 1st equation into the second one to eliminate `V_y`;
`h_y=(2U_y+gT)T/2` and rearrange it to get a quadratic equation,
`gT^2+2U_yT-2h_y=0`

`g=9.81ms^-1, 2U_y=2xx15sin(20)ms^-1, 2h_y=2xx28m`

You will get `T=1.923s` (take the positive one).

Now `R=U_xT=15cos(20)xx1.923m`
`R=27.1m`