A tennis ball is dropped from 1.15 m above the ground. It rebounds to a height of 0.993 m.
1 answer:
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The acceleration is 2 mph/min
Explanation:
The acceleration of an object is the rate of change of velocity. It is defined as follows:
where
v is the final velocity
u is the initial velocity
t is the time taken for the velocity to change from u to v
For the car in this problem, we have (taking North as positive direction):
u = 25 mph
v = 35 mph
t = 5 min
Substituting into the equation, we find the acceleration:
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The speed of the rock at 20 m is 34.3 m/s
Explanation:
We can solve this problem by using the law of conservation of energy: the mechanical energy of the rock, sum of its potential energy + its kinetic energy) must be conserved in absence of air resistance. So we can write:
where :
is the initial potential energy
is the initial kinetic energy
is the final potential energy
is the final kinetic energy
The equation can also be rewritten as follows:
where:
m = 100 kg is the mass of the rock
is the acceleration of gravity
is the initial height
u = 0 is the initial speed (the rock starts at rest)
is the final height of the rock
v is the final speed when h = 20 m
And solving for v, we find:
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