Physical Science 15.2

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At a construction site, a 1.50-kg brick is dropped from rest and hits the ground at a speed of 26.0 m/s. Assuming air resistance can be ignored, calculate the gravitational potential energy of the brick before it was dropped.

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A 10-kg rock is dropped and hits the ground below at a speed of 60 m/s. Calculate the gravitational potential energy of the rock before it was dropped. You can ignore the effects of friction.

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A pendulum with a 1.0-kg weight is set in motion from a position 0.04 m above the lowest point on the path of the weight. What is the kinetic energy of the pendulum at the lowest point? Do not round the answer.

Multiple Choice

What energy conversion occurs as a result of friction?

• chemical energy to thermal energy

• kinetic energy to potential energy

• kinetic energy to thermal energy

• pot

Multiple Choice

At what point in a pendulum’s swing does it have maximum kinetic energy?

• highest point of the swing

• lowest point of the swing

• halfway between the lowest & highest point

• same at all positions of the swing

Multiple Choice

Based on Einstein’s equation for the equivalence of energy and mass, how much energy is produced by the conversion of 1 kilogram of mass to energy?

• 3*10³ J

• 3*10⁵ J

• 9*10⁵ J

• 9*10¹³ J

Multiple Choice

According to the law of conservation of mass, energy can be converted from one from to another but not created or destroyed.

• true

• false