If a cell phone is dropped from a very tall building, how far has the phone fallen after 2.7 seconds, neglecting air resistance?
1 answer:
The free fall of the phone is an uniformly accelerated motion toward the ground, with constant acceleration equal to
So, assuming the downward direction as positive direction of the motion, since the phone starts from rest the distance covered by the phone after a time t is given by
And if we substitute t=2.7 s, we find the distance covered:
So, assuming the downward direction as positive direction of the motion, since the phone starts from rest the distance covered by the phone after a time t is given by
And if we substitute t=2.7 s, we find the distance covered:
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Answer:
A) If the paintball stops completely the magnitude of the change in the paintball’s momentum is
B) If the paintball bounces off its target and afterward moves in the opposite direction with the same speed, the change in the paintball’s momentum is
C) A paintball bouncing off your skin in the opposite direction with the same speed hurts more than a paintball exploding upon your skin because of the strength exerted is twice than if it explodes.
Explanation:
Hi
A) We use the formula of momentum , so we have
B) We use the same formula above, then due we have a change of direction at the same speed, therefore the change in the momentum is the double so
.
C) The average strength of the force an object exerts during impact is determined by the amount the object’s momentum changes. therefore
, as we don't have any data about the impact time but we know momentum is twice, time does no matter and strength is twice too.