The standing vertical jump is a good test of an athlete's strength and fitness. The athlete goes into a deep crouch, then extend
s theirlegs rapidly; when theirlegs are fully extended, theyleave the ground and rise to theirhighest height.It is the force of the ground on the athlete during the extension phase that accelerates the athlete to the final speed with which theyleave the ground.A good jumper can exert a force on the ground equal to twice theirweight. If thecrouch is 65 cm deep, how far off the ground do theyrise
For this exercise we can use the relationship between work and kinetic energy
W = Δx = K_f - K₀
in the exercise they indicate that the strength of the athlete is over twice his weight, therefore the ratio of the floor directed upwards has the same value
F = 2W
F = 2 mg
the displacement is x = 0.65 m, note that the direction of the force and the displacement is the same and the initial velocity is zero due to being crouched at rest, we substitute
F x = ½ m v² - 0
v² = 2 (2mg) x / m
v =
let's calculate
v =
v = 5.05 m / s
already in the air energy is conserved
starting point. Just when it comes off the ground
Em₀ = K = ½ m v²
final point. When is it at the highest part of the trajectory
Scientific evidence is evidence that serves to either support or counter a scientific theory or hypothesis. Such evidence is expected to be empirical evidence and interpretable in accordance with scientific method.
Which best describes the transition from gas to liquid?
gas is @ higher energy state than liq. so the transition must remove energy. so ans is a. Energy must be removed because particles in liquid move more slowly.