C-04 — Work, Power and Energy

According to physics, which expression correctly defines the work done by a constant force?

What is the SI unit of work?

What is the dimension of work?

Force and displacement are vector quantities. What is the nature of work, the product of these two?

A gatekeeper sits on a stool guarding a house all day long. According to physics, how much work has he done?

In this textbook, the force and displacement during work are considered to be in—

You push an object through a distance $s$ by applying a force $F$ and release it. After release, the object travels an additional distance $d$ before stopping. What is the total work done by the applied force?

A moving object comes towards you. You stop it by applying force $F$, but the object pushes you backwards through a distance $s$. How much work is done by the force you applied?

Which best explains the meaning of negative work in physics?

Your mass is 50 kg. Climbing a 10-storied building of 3 m per floor (taking $g = 9.8\,\text{m/s}^2$), the work done is approximately—

What is energy?

Energy is a—

The unit and dimension of energy are the same as those of—

Doing positive work on an object means—

If a force performs negative work on an object, then—

You move an object 10 m by applying a force of 100 N. The work done by you is—

In the situation above, a frictional force of 10 N acts in the opposite direction. The work done by friction is—

Energy lost due to friction is mostly converted into—

Energy that arises due to the position, shape and motion of an object is called—

The two forms of mechanical energy are—

Which of the following is NOT a form of energy mentioned in the chapter?

The kinetic energy of an object of mass $m$ moving with velocity $v$ is—

If the velocity of an object is doubled, its kinetic energy becomes—

A force of 10 N acts on a stationary object of mass 10 kg for 10 s. The kinetic energy at the end of 10 s is—

In the above scenario, what is the kinetic energy 20 s after the force has been removed (force applied only for first 10 s)?

If the same 10 N force is applied for 20 s on the same 10 kg stationary object, the kinetic energy is—

The kinetic energy of a 10 kg object is 80 J. Its velocity is—

If an object moving with velocity $u$ undergoes work $W$ done on it, its new kinetic energy is—

Severe road accidents at high speed are mainly due to—

Consider the following about kinetic energy:

Potential energy is energy stored due to the—

The potential energy stored in a spring of constant $k$ compressed by $x$ is—

The gravitational potential energy of a body of mass $m$ at height $h$ is—

A body of mass 10 kg falls on a spring with velocity 10 m/s. If $k = 100{,}000\,\text{J/m}^{2}$, the compression of the spring is—

A body of mass 10 kg is thrown upwards with a velocity of 100 m/s. The maximum height reached (taking $g = 9.8\,\text{m/s}^{2}$) is approximately—

A body of mass 5 kg is thrown upwards with a velocity of 50 m/s. The height at which kinetic energy equals potential energy is approximately—

Using conservation of energy, the velocity of a body falling from height $h$ on reaching the ground is—

The restoring force exerted by a spring compressed by amount $x$ is—

To lift an object of mass $m$, the upward force that must be applied equals—

Consider the following statements about a stretched/compressed spring:

The history of human civilization can be largely understood as the history of—

Which of the following is NOT a fossil fuel?

Crude oil extracted from underground is refined to give—

The main constituent of natural gas is—

The fuel typically used in nuclear power plants is—

According to the chapter, the world's known sources of fossil and uranium fuel will be exhausted within—

The Sun and stars produce energy by which process?

The fuel for nuclear fusion that humans hope to use in the future is obtained from an isotope of—

Approximately what fraction of the world's energy currently comes from renewable sources?

The largest single contributor to renewable energy in the world is—

Hydroelectricity is generated by—

After hydroelectricity, the largest renewable source of energy is—

Which of the following are examples of biomass?

According to the chapter, one square kilometre receives solar energy of approximately—

The annual growth rate of wind energy use is approximately—

Which country is mentioned as having started large-scale biofuel use?

Geothermal energy is obtained from—

Consider the following statements about solar energy:

Burning fossil fuels mainly releases which greenhouse gas?

The gradual increase in Earth's temperature due to greenhouse gases is called—

As a consequence of global warming, Bangladesh is most threatened by—

A nuclear power plant differs from a coal power plant in that it—

Which two are mentioned as major nuclear power plant accidents?

Consider the following environmental impacts of building a hydroelectric dam:

Which is the law of conservation of energy?

In an oscillating pendulum (no friction), energy continuously transforms between—

In a freely oscillating pendulum, the velocity is maximum at—

When a stone hits the ground and stops, its kinetic energy is mostly converted into—

In an electric fan or motor, electrical energy is converted into—

In an electric iron or heater, electrical energy is converted into—

In a light bulb, tube light or LED, electrical energy is converted mainly into—

In a loudspeaker, electrical energy is converted into—

While charging a mobile battery, electrical energy is converted into—

Burning cooking gas converts chemical energy into—

The light from a candle is an example of—

In a petrol or diesel engine, chemical energy is converted into mechanical energy via the intermediate form of—

A discharging battery is an example of conversion from—

In a generator, the energy transformation is—

When two surfaces rub, mechanical energy is mostly transformed into—

Inside a microwave oven, electromagnetic waves are converted into—

A solar cell directly converts—

When light strikes a photosensitive photographic film, light energy is converted into—

A perpetual motion machine of the kind described (motor → generator → motor) is impossible because—

When energy is transformed from one form to another, the dissipated portion appears mainly as—

In a thermocouple, energy transformation is—

Einstein's mass-energy relation is—

The value of the speed of light $c$ is approximately—

The number of protons and neutrons in $\ce{^{235}_{92}U}$ are respectively—

Natural abundance of $\ce{^{235}U}$ is approximately—

The half-life of $\ce{^{235}U}$ is approximately—

When $\ce{^{235}U}$ captures a slow neutron, it splits mainly into—

In a nuclear chain reaction, the released neutrons—

The function of a control rod in a nuclear reactor is to—

The destruction of Hiroshima and Nagasaki by nuclear bombs is an example of—

Consider the following about nuclear power generation:

Power is defined as—

The SI unit of power is—

The dimension of power is—

Power is a—

A 100 W bulb consumes electrical energy at the rate of—

A 1000 MW nuclear power plant produces electrical energy at the rate of—

Efficiency of a machine is given by—

A 1000 W motor lifts a 10 kg object 10 m in 15 s. Its efficiency is approximately—

In the same problem above, the energy wasted is—

If 10% of energy is wasted at each step, the overall efficiency after 4 steps is approximately—

Considering all the wastage steps, the overall efficiency of a power plant can drop down to as low as—

Which is the unit of work?

A body of 5 kg is kept at 20 cm, 30 m, 40 cm and 50 cm height respectively. At which position is its potential energy a maximum?

From the velocity-time graph (Figure 4.09), in which part does velocity increase in proportion to time?

From the velocity-time graph (weight of car 1000 kg, peak velocity 15 m/s), the maximum kinetic energy is—

From the law of conservation of energy it is found:

What type of energy is stored when a spring is stretched?

A boy of mass 40 kg and a young man of mass 60 kg start from the ground floor and reach the rooftop at the same time, both running at 30 m/min. Whose power is greater?

A 1 kW motor lifts 2000 litres of water to a second-floor (20 m) rooftop tank in 10 minutes. The gravitational potential energy gained by the water is approximately—

A 1 kW motor lifts 2000 L of water to a 20 m height in 10 min. A 2 kW motor lifts 3000 L of water to a 40 m height in 15 min. Which motor is more economical (in terms of efficiency)?

When an object is lifted vertically upward from the ground, the work done by the lifting force is—

If the efficiency of an electric bulb is 70%, it means—

Which statement about kinetic energy and velocity is correct?

Nuclear chain reaction is a process in which—