A machine that operates a ride at the fair requires 2500 J to lift a 294 N child 5.0 m. What is the efficiency of this machine?
1 answer:
Answer:
η = 58.8%
Explanation:
Work is defined as the force applied by the distance traveled by the body.
where:
W = work [J] (units of joules)
F = force = 294 [N]
d = distance = 5 [m]
Efficiency is defined as the energy required to perform an activity in relation to the energy actually added to perform some activity. This can be better understood by means of the following equation.
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Complete question:
A child sits in a wagon with a pile of 0.64-kg rocks. If she can throw each rock with a speed of 7.5 m/s relative to the ground, causing the wagon to move, how many rocks must she throw per minute to maintain a constant average speed against a 3.9-N force of friction
Answer:
The number of rocks per minutes thrown is 49 rocks/min
Explanation:
Given;
mass of the rock, m = 0.64 kg
speed of the rock, v = 7.5 m/s
frictional force, = 3.9 N
For an object to move at a constant speed, the applied force must be equal to the frictional force.
where;
is the applied force
N/t is the number of rocks per minutes thrown
Substitute the given parameters;
Approximately 49 rocks/min