Intro to Conservation of Energy Video Lessons

Concept

# Problem: 1. A bow is drawn so that it has 40 J of potential energy. When fired, the arrow will ideally have a kinetic energy that isA) less than 40 J.B) more than 40 J.C) 40 J.D) impossible to predict without additional information2. When a car is braked to a stop, its kinetic energy is transformed toA) stopping energy.B) potential energy.C) energy of motion.D) energy of rest.E) heat.3. A hydraulic press, like an inclined plane, is capable of increasing energy.A) sometimes trueB) always falseC) always trueD) sometimes false4. A hydraulic press, like a wheel and axle, is capable of multiplying force input.A) always trueB) always falseC) sometimes trueD) sometimes false5. After rolling halfway down an incline a marbleʹs kinetic energy isA) less than its potential energy.B) greater than its potential energy.C) the same as its potential energy.D) impossible to determine.6. The ball rolling down an incline has its maximum potential energy atA) the top.B) a quarter of the way down.C) halfway down.D) the bottom.7. A ball rolling down an incline has its maximum kinetic energy atA) the top.B) halfway down.C) three-quarters of the way down.D) the bottom.8. A block of ice sliding down an incline has its maximum speed atA) the top.B) the bottom.C) halfway down.D) difficult to predict without knowing the slope of the inclineE) difficult to predict without knowing the coefficient of friction

###### FREE Expert Solution

1.

Law of conservation of energy:

$\overline{){{\mathbf{K}}}_{{\mathbf{i}}}{\mathbf{+}}{{\mathbf{U}}}_{{\mathbf{i}}}{\mathbf{+}}{{\mathbf{W}}}_{{\mathbf{nc}}}{\mathbf{=}}{{\mathbf{K}}}_{{\mathbf{f}}}{\mathbf{+}}{{\mathbf{U}}}_{{\mathbf{f}}}}$, where Wnc is the work done by non-conservative forces such as friction.

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###### Problem Details

1. A bow is drawn so that it has 40 J of potential energy. When fired, the arrow will ideally have a kinetic energy that is
A) less than 40 J.
B) more than 40 J.
C) 40 J.
D) impossible to predict without additional information

2. When a car is braked to a stop, its kinetic energy is transformed to
A) stopping energy.
B) potential energy.
C) energy of motion.
D) energy of rest.
E) heat.

3. A hydraulic press, like an inclined plane, is capable of increasing energy.
A) sometimes true
B) always false
C) always true
D) sometimes false

4. A hydraulic press, like a wheel and axle, is capable of multiplying force input.
A) always true
B) always false
C) sometimes true
D) sometimes false

5. After rolling halfway down an incline a marbleʹs kinetic energy is
A) less than its potential energy.
B) greater than its potential energy.
C) the same as its potential energy.
D) impossible to determine.

6. The ball rolling down an incline has its maximum potential energy at
A) the top.
B) a quarter of the way down.
C) halfway down.
D) the bottom.

7. A ball rolling down an incline has its maximum kinetic energy at
A) the top.
B) halfway down.
C) three-quarters of the way down.
D) the bottom.

8. A block of ice sliding down an incline has its maximum speed at
A) the top.
B) the bottom.
C) halfway down.
D) difficult to predict without knowing the slope of the incline
E) difficult to predict without knowing the coefficient of friction