Question

frictien ma t3kes oh itortso ntaling down from the top of a sk jump with negligible and takes off horizontally If h = 6.70 m and D = 10.1 m, find H. Enviar Respuesta Tries 0/12 Find her total kinetic energy as she reaches the ground Enviar Respuesta Tries 0/12

Answer 1

She takes off horizontally, so let the velocity be V in this direction. By the time she covers horizontal distance D, she also covers vertical distance h.

Finding time for covering h:

vertical velocity = 0

Using cinematic equation: h = u*t + 0.5*a*t²

So, 6.7 = 0 + 0.5*9.8*t²

So, t² = 1.37s

t = 1.17s

In the same time D is covered.

So, D = V*t..... (No acceleration in x direction)

10.1 = V*1.17; thus V = 8.63m/s.

Energy will be conserved from top point (1) to the point of take off (2).

So, KE1 + PE1 = KE2 + PE2

So, 0.5*63*0 + 63*9.8*H = 0.5*63*8.63² + 63*9.8*6.7

So, H = (2346.02 + 4136.58) / 63*9.8

H = 10.54m

The energy will remain same when she reaches the ground

63*9.8*H = 0.5*63*u²

u² = 63*9.8*10.54/0.5*63 = 206.58

u = 14.37m/s.