Answer:
![v=(800)/(√(3) ) m/s](https://img.qammunity.org/2020/formulas/physics/high-school/43bnt1amaswsdjz7n11fprhs8axrlvep1m.png)
Step-by-step explanation:
Given that,
A body is projected at an angle of 45°(β) with an intial elevation .
We can see that there will be no change in the horizontal component of velocity. Let the velocity of projection be v.
would be the horizontal component.
Now we see that the time taken to decent from the maximum height of
, the body will cover a horizontal distance of
.
At the maximum height vertical component of velocity is zero so the time taken to fall is given by:-
![vcos\beta *t=x_(2)](https://img.qammunity.org/2020/formulas/physics/high-school/yw1b6m4919glkh3bemvrxwbtbrw8a1bgnj.png)
![\beta =45](https://img.qammunity.org/2020/formulas/physics/college/ya42qlhj8xgh9at5fwsyps1m0nvfcnz0c0.png)
![x_(2)=8000m](https://img.qammunity.org/2020/formulas/physics/high-school/nn8lb8l1t3z1jk0cmk0gvrpsbikd070rww.png)
![t=\sqrt{(2y_(2) )/(g) }](https://img.qammunity.org/2020/formulas/physics/high-school/qshhknumw2jfz7aifz8qqwt35egaf2s60x.png)
![t=10√(6) s](https://img.qammunity.org/2020/formulas/physics/high-school/8nfn5fwwx3c7xk5ycdl9edfk8o3odn2ac2.png)
On the substituting t in abow expression we get
![v=(800)/(√(3) ) m/s](https://img.qammunity.org/2020/formulas/physics/high-school/43bnt1amaswsdjz7n11fprhs8axrlvep1m.png)