Question

In an action movie, a stuntman leaps from the top of one building to the top of another building 5.2 m away. After a running start, he leaps at a velocity of 6.0 m/s at an angle of 15° above horizontal. Will he make it to the other roof, which is 2.9 m shorter than the building he jumps from?

Answer 1

stuntman's vertical velocity is vy= 6 sin 15=1.55m/s. Height that he goes up is, vertical kinetic energy = mgh 1/2 v² = gh, h=v²/(2g)=0.12 m. time wanted to go up= vy/9.8=0.16s, Time to fall through a height 0.12+2.9=3.02m is t=sqrt(3.02*2/9.8)=0.78 s Total time needed to go up and down is 0.78+0.16=0.94 s. to calculate the horizontal range, Horizontal velocity = 6 cos 15=5.8 m/s. Distance which he can cover is 5.8*0.94=5.44 m. If the distance between the two building is less than 5.44 m then he will be safe and he can jump that distance.