Julie throws a ball to her friend Sarah. The ball leaves Julie's hand a distance 1.5 meters above the ground with an initial spe
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given,
mass of the bar, m = 30 Kg
distance of rise, h = 0.60 m
Assuming the efficiency = 25 %
energy from the pizza slice = 300 C = 1260 kJ
To consume Energy from the pizza bar is to be pulled several number of time.
( energy from pizza ) x (efficiency) = n m g h
n is the number of lift
( 1260 x 10³) x (0.25) = n x 30 x 9.8 x 0.6
n = 1786 times.
Weightlifter should lift bar 1786 times to burn off the energy.
Answer:
1) 0.43 meters per second
2) 0.21 meters per second
3) 1.02
4) 0.66 seconds
Explanation:
part 1
By conservation of energy, the maximum kinetic energy (K) of the block is at equilibrium point where the potential energy is zero. So, at the equilibrium kinetic energy is equal to maximum potential energy (U):
With m the mass, v the speed, k the spring constant and xmax the maximum position respect equilibrium position. Solving for v
part 2
Again by conservation of energy we have kinetic energy equal potential energy:
part 3
Acceleration can be find using Newton's second law:
with F the force, m the mass and a the acceleration, but elastic force is -kx, so:
part 4
The period of an oscillator is the time it takes going from one extreme to the other one, that is going form 4.5 cm to -4.5 cm respect the equilibrium position. That period is:
So between 0 and 4.5 cm we have half a period: