projectile (1 Viewer)

[omgmynameislong]

A long jumper left the ground at an angle of 15 degrees and jumped a distance of 7.0m. Considering this result, calculate the velocity of the long jumper leaving the ground.

??????

 

[omgmynameislong]

R= u^2sin2theta/g

from projectile motions and you get 11.7ms^-1

but I don't know how to do it using the physics equations :\.

 

[Pwnage101]

A long jumper left the ground at an angle of 15 degrees and jumped a distance of 7.0m. Considering this result, calculate the velocity of the long jumper leaving the ground.

??????

we know 7=Ux*t=U*cos(15)*t---->Ut=7sec(15)...(1)

Sy=Uyt+0.5at^2

0=Usin(15)t-4.9*t^2 ---> 0=Ut(sin15)-4.9t^2...(2)

we can solve this by substituting (1) in (2) which will leave us with one equation in one unknown:

0=7sec(15)(sin15)-4.9(t^2)
0=7tan15-4.9t^2

solve for t

sub back in (1) to get U.

I believe these kinds of questions havent been asked at SHC level because they require solving similtaneous equations.