.111 U.S. Cellular 12:23 PM blackboard.ecu.edu In Class Assignment Projectile Mo

Question

.111 U.S. Cellular 12:23 PM blackboard.ecu.edu In Class Assignment Projectile Motion Introduction In many sport activities the performer moves freely through the air. Diving, gymnastics, high jumping, long jumping and figure skating are a few examples. In addition, sport implements are projected in events like shot put, discus throwing and baseball In both cases, movements are classified under the heading of projectile motion and are controlled by physical laws. Once the performer or projectile is in the air, only two external forces act upon it. The first is that due to gravity and the second is air resistance. The latter force is important in sports such as ski jumping or skydiving because of high velocities. However in most cases air resistance is very small and is ignored Projectile motion is govened by the following equations: Vf= vi + at vf 2 = vi 2 +2ad d = Vi t +.5at2 A 60 kg diver performs a handstand dive from the 3 m tower. The diver's center of mass is 1.5 m above her hands in this position. Compute the following: a) The time to hit the water (the hands will enter the water fully extended) b) The diver's velocity at impact

Explanation / Answer

part a )

handstnd dive there is only vertical velocity componet

time taken to reach at water surface

d = u*t + 1/2 * at^2

assume upward direction is positive and downward is negative

given : d = -3 m

vi = 0 because handstand dive is like free fall

a = -g = -9.8 m/s^2

-3 = 0*t + 1/2 * -9.8*t^2

t^2 = -6/9.8 = 0.61 s

t = sqrt(0.61) = 0.78s

part b )

velocity of diver when he hit at water surface

v^2 = u^2 + 2as

u = 0

a = -9.8 m/s^2

s = -3 m

v = sqrt(2*-9.8*3)

v = 7.67 m/s

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