Concept Items
9.1 Work, Power, and the Workâ€“Energy Theorem

No, because the workenergy theorem states that work done on an object is equal to the change in kinetic energy, and change in KE requires a change in velocity. It is assumed that mass is constant.

No, because the workenergy theorem states that work done on an object is equal to the sum of kinetic energy, and the change in KE requires a change in displacement. It is assumed that mass is constant.

Yes, because the workenergy theorem states that work done on an object is equal to the change in kinetic energy, and change in KE requires a change in velocity. It is assumed that mass is constant.

Yes, because the workenergy theorem states that work done on an object is equal to the sum of kinetic energy, and the change in KE requires a change in displacement. It is assumed that mass is constant.

Work is defined as the ratio of the force over the distance.

Work is defined as the sum of the force and the distance.

Work is defined as the square of the force over the distance.

Work is defined as the product of the force and the distance.
A book with a mass of 0.30 kg falls 2 m from a shelf to the floor. This event is described by the workâ€“energy theorem: $$W=\text{}fd\text{=}\frac{1}{2}m{v}_{2}^{2}\xe2\u02c6\u2019\frac{1}{2}m{v}_{1}^{2}$$ Explain why this is enough information to calculate the speed with which the book hits the floor.
 The mass of the book, m, and distance, d, are stated. F is the weight of the book mg . v_{1} is the initial velocity and v_{2} is the final velocity. The final velocity is the only unknown quantity.
 The mass of the book, m, and distance, d, are stated. F is the weight of the book mg . v_{1} is the final velocity and v_{2} is the initial velocity. The final velocity is the only unknown quantity.
 The mass of the book, m, and distance, d, are stated. F is the weight of the book mg . v_{1} is the initial velocity and v_{2} is the final velocity. The final velocity and the initial velocities are the only unknown quantities.
 The mass of the book, m, and distance, d, are stated. F is the weight of the book mg . v_{1} is the final velocity and v_{2} is the initial velocity. The final velocity and the initial velocities are the only unknown quantities.
9.2 Mechanical Energy and Conservation of Energy

While going up, the personâ€™s KE would change to PE. While coming down, the personâ€™s PE would change to KE.

While going up, the personâ€™s PE would change to KE. While coming down, the personâ€™s KE would change to PE.

While going up, the personâ€™s KE would not change, but while coming down, the personâ€™s PE would change to KE.

While going up, the personâ€™s PE would change to KE, but while coming down, the personâ€™s KE would not change.

v = h

v = \sqrt{2h}

v = gh

v = \sqrt{2gh}
The starting line of a cross country foot race is at the bottom of a hill. Which form(s) of mechanical energy of the runners will change when the starting gun is fired?
 Kinetic energy only
 Potential energy only
 Both kinetic and potential energy
 Neither kinetic nor potential energy
9.3 Simple Machines

It reduces the input force and the output force.

It reduces the input force and increases the output force.

It increases the input force and reduces the output force.

It increases the input force and the output force.
Which type of simple machine is a knife?
 A ramp
 A wedge
 A pulley
 A screw