An unwary football player collides with a padded goalpost while running at a velocity of 7.50 m/s and comes to a full stop after compressing the padding and his body 0.350 m. (a) What is his deceleration?(b) How long does the collision last?

(a) the deceleration of the player is -80.36 m/s²

(b) the time the collision last is 0.093 s

Explanation:

Given;

Initial velocity of the football player, u = 7.50 m/s

Final velocity of the football player, v = 0

distance traveled = compression of the pad, s = 0.35 m

Part (a) the deceleration of the player

v² = u² + 2as

0 = 7.5² + (2 x 0.35)a

0 = 56.25 + 0.7a

- 56.25 = 0.7a

a = -56.25 / 0.7

a = -80.36 m/s²

Part (b) the time the collision last

v = u + at

t = (v - u)/a

t = (0 - 7.5)/ -80.36

t = - 7.5 / -80.36

t = 0.093 s

r = ρ x length / area  

ρ = r x area / length  

ρ is in ohm-meters  

in basic units, it is m³kg/s³a²  

i think this is it.

force required to detach it is given by

charges are taken to be fundamental charge

now we have

so above is the minimum distance at which it will detach