Explain why , a runner presses the ground with his feet before he start his run.

In order to make a jump straight up, a 60 kg player starts the motion crouched down at rest. He pushes hard against the ground, raising his centre of mass by a height h_(0) = 0.5 m . Assume that his legs exert a constant force F_(0) during this motion. At this point, where his centre of mass has gone up by h_(0) his feet leave the ground and he has an upward velocity of v . Centre of mass of his body rises further by h = 0.8 m before falling down [Take g = 10 m//s^(2) ] (a) Find v . (b) Find the normal force applied by the ground on his feet just before he left the ground.

Statement -1 : A man standing on the ground has to hold his umbrella at an angle theta with the vertical to protect himself from rain. It is possible that the man now starts running on the ground with certain speed, but he still has to hold his umbrella at angle theta with the vertical to protect himself from rain. Statement -2 : Vertical component of velocity of rain w.r.t man does not change. if he starts running on a horizontal ground.

Statement -1 : A man standing on the ground has to hold his umbrella at an angle theta with the vertical to protect himself from rain. It is possible that the man now starts running on the ground with certain speed, but he still has to hold his umbrella at angle theta with the vertical to protect himself from rain. Statement -2 : Vertical component of velocity of rain w.r.t man does not change. if he starts running on a horizontal ground.

A monkey climbs 30 feet at the beginning of each hour and rests for while he slips back 20 feet before he again starts climbing in the beginning of the next hour. If he begins his ascent at 8.00 at what time will he first touch a flag at 120 feet from the ground?