Work and power, efficiency Questionbank

A constant horizontal force $F$ is applied to a block, moving it a distance $d$ across a horizontal floor at a constant velocity. Which of the following represents the work done by the force $F$?

When work is done on an object without any energy being dissipated as heat, the work done is exactly equal to the change in the object's total __________.

When a ball is thrown vertically upwards, which of the following best describes the work done by gravity on the ball during its ascent?

Which of the following describes a situation where the work done is negative?

For an ideal mechanical system moving at a constant speed, power $P$ can be calculated using the force $F$ and velocity $v$ as $P = \dots\dots\dots\dots\dots$.

An electric kettle with a power rating of $1.5\text{ kW}$ is used for $3.0\text{ min}$. How much energy is transferred to the kettle during this time?

In mechanical systems, 'wasted' energy is most commonly transferred to the surroundings in the form of __________.

An electric car motor produces $50\ \text{kW}$ of power to keep the car moving at a constant speed of $25\ \text{m s}^{-1}$. What is the magnitude of the total resistive forces (friction and air resistance) acting against the car?

True or False: It is possible for a highly advanced machine to have an efficiency of $105\%$ if it uses superconducting materials.

A worker uses a ramp to push a crate with a weight of $800\ \text{N}$ to a height of $2.0\ \text{m}$. The worker applies a force of $250\ \text{N}$ parallel to the ramp over a distance of $8.0\ \text{m}$. What is the efficiency of the ramp system?