Kinetic energy is a type of mechanical energy that a particle or system has by virtue of its motion. When work (transferring of energy) is done on a body by exerting a net force, the body accelerates and acquires kinetic energy. Kinetic energy is a characteristic of a moving particle or system and relies not only on its movement but also on its internal mass. This type of motion could be a translational, vibration, rotation about an axis, or any combination of motion. A body’s translational kinetic energy is equal to one-half multiplied by its mass (m) and the square of the velocity (v). K<sub>E</sub> = 1/2mv<sup>2</sup>
Joule is the basic unit of energy.
Work is the measure of energy transmission that happens when a body is displaced over a length by an outside force, at least a section of which is exerted in the same direction of the generated displacement. If the applied force is constant, the work done could be found by multiplying the path’s length by the component of the applied force acting along the displaced path. We represent this idea mathematically; the work is equal to the force times the distance covered, W = fd. This can be considered as the kinetic energy and work done connection.
Suppose the given force is applied at an angle “θ” to the displacement; in this case, W =fd cos θ. The work done on an object is achieved not only by the displacement of the object from one position to another but also by compression, rotation, and interaction of particles in various physical fields.
Important Kinetic Energy and Work Done Questions with Answers
1) What is meant by energy?
In physical science, energy is the physical property that is transmitted to a particle or to a system, recognisable in the functioning of work and in the form of light and heat. Energy is also a conserved quantity. The energy conservation law states that any type of energy can be converted into another form, but at the same time, it cannot be created or destroyed. The SI measurement unit is the joule (J).
2) What are the two types of mechanical energy?
There are two fundamental types of mechanical energy – potential energy and kinetic energy. Mechanical energy totally depends on the motion and position of the object. The power of the object comes from the sum of potential and kinetic energy. In fact, when a body’s potential energy is paired with its kinetic energy, it produces mechanical energy.
3) What is meant by work done?
In order to displace a body, energy must be transferred to it. Energy is transferred through the application of force. This measure of energy transmitted by force to displace a body is called work done.
4) Give the relationship between work done and kinetic energy.
Energy and work are directly proportional to each other. Work completed by the body can be mathematically represented as:
W = (½mvvf) – (½mv2i)
Where,
W is the work completed by the body measured in joules.
m is the mass of the body calculated in kilograms.
vi is the initial velocity of the body measured in m/s.
vf is the final velocity of the object measured using m/s.
5) Which of the following types of energy relies on the square of the body’s speed and mass?
A) Potential
B) Kinetic
C) Nuclear
D) Electrostatic
Answer: B) Kinetic energy
Explanation: The kinetic energy, nuclear energy, and gravitational potential energy heavily depend on the mass of the objects. However, kinetic energy is the only quantity that has the term square of velocity.
6) Explain how engineers use the work-energy principle.
Engineers utilise the work-energy principle to find the work done by individual progressive elements of the engine during its chain of movements. By measuring the variation in work completed, engineers can smoothly isolate the functioning of individual parts of the drivetrain and try to enhance its efficiency.
7) What is the basic unit of energy?
Joule is the basic unit of energy.
8) Kinetic energy is a type of mechanical energy that a particle or system has by virtue of its ________.
Answer: motion
Explanation: Kinetic energy is a type of mechanical energy that a particle or system has by virtue of its motion.
9) A body’s translational kinetic energy is equal to one-half multiplied by its _______ and the square of the velocity (v).
Answer: mass (m)
Explanation: A body’s translational kinetic energy is equal to one-half multiplied by its mass (m) and the square of the velocity (v).
10) What are various ways of doing work?
The work done on an object is achieved not only by the displacement of the object from one position to another but also by compression, rotation, and interaction of particles in various physical fields.
11) What is the most basic mathematical representation of work?
The work is equal to the force times the distance covered, W = fd.
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Practice Questions
1) What is meant by kinetic energy?
2) What are the differences between kinetic energy and potential energy?
3) What is meant by mechanical energy?
4) What is meant by work done?
5) What is the relationship between acceleration, mass, force, and work?
6) What are the factors that affect kinetic energy?
7) What are the factors that affect potential energy?
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