<<–2/”>a >h4 style=”text-align: center;”>Speed
An object is said to be in motion if it changes its position with time, with respect to its surroundings.Speed is defined as the distance moved per unit time,
i.e Speed =Distance /Time
When we say that an object is at rest or in motion,then this statement is incomplete and meaningless. Basically, rest & motion are relative terms.
An object which is at rest can also be in motion simultaneously. This can be illustrated as follows.
The passengers sitting in a moving bus are at rest with respect to each other but they are also in motion at the same time with respect to the objects like trees, buildings on the road side. So the motion and rest are relative terms.
Velocity
Velocity indicates the rate of change of the object’s position (r ); i.e., velocity tells you how fast the object’s position is changing. The magnitude of the velocity (|| v || ) indicates the object’s speed. The direction of the velocity (dir v ) indicates the object’s direction of motion. The velocity at any point is always tangent to the object’s path at that point. Thus, the velocity tells you how the object is moving. In particular, the velocity tells you which way and how fast the object is moving.
Gravity
Gravitation is the force by which every mass or particle of matter, including photons, attracts and is attracted by every other mass or particle of matter.The gravitational field at any point P in space is defined as the Gravitational Force felt by a tiny unit mass placed at P.
Every particle of matter in the universe attracts every other particle with a force that is directly proportional to the product of the masses of the particles and inversely proportional to the square of the distance between them.
Mathematically, this law, and the magnitude of the force due to the gravitational interaction between two particles, is expressed with :-
Properties of Gravitational Force.
It is always attractive in nature while electric and magnetic force can be attractive or repulsive.
It is independent of the medium between the particles while electric and magnetic force depend on the nature of the medium between the particles.
It holds good over a wide range of distances. It is found true for interplanetary to inter atomic distances.
It is a central force i.e. acts along the line joining the centres of two interacting bodies.
It is a two body interaction i.e. gravitational force between two particles is independent of the presence or absence of other particles.
It is the weakest force in nature : As Fnuclear > F electromagnetic > F gravitational .
It is a conservative force i.e. work done by it is path independent or work done in moving a particle round a closed path under the action of gravitational force is zero.
It is an action reaction pair i.e. the force with which one body (say earth) attracts the second body (say moon) is equal to the force with which moon attracts the earth.
Mass
It is the measure of the quantity of matter in an object and its unit is kilogram (kg) in SI units. It depends on the number of Molecules in the matter and their masses and does not depend on gravity. Therefore an object would have same mass on Earth and on the Moon but different weight because of the change of gravity. Gravity on the moon is 1/6th of the gravity on earth. Mass of an object can be measured by using spring balance (newton-meter), top pan balance or lever balance. The international definition of mass is It is equal to the mass of the international prototype of the kilogram made up of platinum-iridium Alloy kept at international bureau of weights and measurements in Paris.
Mass is the amount of matter in an object. It can also be defined as the property of a body that causes it to have weight in a gravitational field. It is important to understand that the mass of an object is not dependent on gravity. Bodies with greater mass are accelerated less by the same force.
Weight
The weight of an object is defined as the force of gravity on the object and may be calculated as the mass times the acceleration of gravity, w = mg. Since the weight is a force, its SI unit is the newton.
For an object in free fall, so that gravity is the only force acting on it, then the expression for weight follows from Newton’s second law.
Force
Force is any interaction that, when unopposed, will change the motion of an object. A force can cause an object with mass to change its velocity (which includes to begin moving from a state of rest), i.e., to accelerate.
Impact
Impact is a high force or shock applied over a short time period when two or more bodies collide. Such a force or acceleration usually has a greater effect than a lower force applied over a proportionally longer period.
Work
Work is said to be done when a force applied on the body displaces the body through a certain distance in the direction of force.Mathematically, work is the force-displacement product
W = F x s cos a
or the force-displacement path integral
dW = F · ds
Positive work means that force (or its component) is parallel to displacement. Negative work means that force (or its component)is opposite to displacement i.e. In conservative field work done by the force over a closed loop is zero.
Power
Power is defined as the rate at which work is done. Its unit is watt Power is said to be one watt, when one joule of work is said to be done in one second.
If work is being done by a machine moving at speed v against a constant force, or resistance, F, then since work done is force times distance, work done per second is Fv, which is the same as power.
Power = Fv
Energy
Energy is the capacity for doing work. Energy can manifest itself in many forms like mechanical energy, thermal energy, electric energy, chemical
energy, Light energy, Nuclear Energy, etc.
The energy possessed by a body due to its position or due to its motion is called mechanical energy. The mechanical energy of a body consists of potential energy and kinetic energy.
Potential energy is the energy of a body or a system with respect to the position of the body or the arrangement of the particles of the system.For example, gravitational potential energy is associated with the gravitational force acting on object’s mass; elastic potential energy with the elastic force (ultimately electromagnetic force) acting on the elasticity of a deformed object; electrical potential energy with the coulombic force; strong nuclear force or weak nuclear force acting on the electric charge on the object; chemical potential energy, with the chemical potential of a particular atomic or molecular configuration acting on the atomic/molecular structure of the chemical substance that constitutes the object; thermal potential energy with the electromagnetic force in Conjunction with the temperature of the object.
Kinetic energy of an object is the energy that it possesses due to its motion. It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity.
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Speed, velocity, gravity, mass, weight, force, impact, work, power, and energy are all fundamental concepts in physics. They are all interrelated, and a deep understanding of one concept can help you to better understand the others.
Speed is the rate at which an object is moving. It is measured in meters per second (m/s). Velocity is speed in a specific direction. It is also measured in m/s, but it includes a direction as well. For example, if you are driving a car at 60 mph north, your velocity is 60 mph north.
Gravity is a force that attracts objects to each other. The more massive an object is, the stronger its gravitational pull. The Earth’s gravity pulls us down to the ground, and the Moon’s gravity pulls the tides in and out.
Mass is a measure of how much matter is in an object. It is measured in kilograms (kg). Weight is the force of gravity on an object. It is measured in newtons (N). The weight of an object is equal to its mass times the acceleration due to gravity. The acceleration due to gravity on Earth is 9.8 m/s^2, so the weight of a 1-kg object is 9.8 N.
Force is any interaction that causes an object to change its motion. It is measured in newtons (N). The force of gravity is a force, as is the force of friction.
Impact is the collision of two objects. The force of impact is equal to the product of the masses of the objects and the change in their velocities.
Work is done when a force moves an object. It is measured in joules (J). The amount of work done is equal to the force times the distance moved.
Power is the rate at which work is done. It is measured in watts (W). The power of an object is equal to the work done divided by the time it takes to do the work.
Energy is the ability to do work. It is measured in joules (J). There are many different forms of energy, including kinetic energy, potential energy, and thermal energy.
Kinetic energy is the energy of motion. It is equal to one-half the mass of an object times the square of its velocity.
Potential energy is the energy stored in an object due to its position or state. For example, a ball held above the ground has potential energy due to its height. When the ball is released, it falls and its potential energy is converted into kinetic energy.
Thermal energy is the energy of motion of the atoms and molecules in a substance. It is measured in degrees Celsius (°C) or Kelvin (K).
All of these concepts are important in physics, and they are all interrelated. A deep understanding of one concept can help you to better understand the others.
Speed is the rate at which an object moves in a particular direction. It is measured in meters per second (m/s).
Velocity is the rate at which an object moves in a particular direction and includes the object’s speed and direction. It is measured in meters per second (m/s).
Gravity is a force that attracts objects to each other. It is the force that keeps us on the Earth and causes objects to fall. The strength of gravity depends on the mass of the objects involved and the distance between them.
Mass is the amount of matter in an object. It is measured in kilograms (kg).
Weight is the force of gravity on an object. It is measured in newtons (N).
Force is a push or pull that can change the motion of an object. It is measured in newtons (N).
Impact is the collision of two or more objects. It can cause damage to the objects involved.
Work is the transfer of energy from one object to another. It is measured in joules (J).
Power is the rate at which work is done. It is measured in watts (W).
Energy is the ability to do work. It can be stored in many different forms, such as heat, light, and electricity.
Frequently Asked Questions
What is the difference between speed and velocity?
Speed is the rate at which an object moves in a particular direction. It is measured in meters per second (m/s). Velocity is the rate at which an object moves in a particular direction and includes the object’s speed and direction. It is measured in meters per second (m/s).
What is the difference between mass and weight?
Mass is the amount of matter in an object. It is measured in kilograms (kg). Weight is the force of gravity on an object. It is measured in newtons (N).
What is the difference between force and impact?
Force is a push or pull that can change the motion of an object. It is measured in newtons (N). Impact is the collision of two or more objects. It can cause damage to the objects involved.
What is the difference between work and power?
Work is the transfer of energy from one object to another. It is measured in joules (J). Power is the rate at which work is done. It is measured in watts (W).
What is the difference between energy and power?
Energy is the ability to do work. It can be stored in many different forms, such as heat, light, and electricity. Power is the rate at which work is done. It is measured in watts (W).
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A car is moving at a constant speed of 60 miles per hour. What is the car’s velocity?
(A) 60 miles per hour
(B) 60 miles per hour north
(C) 60 miles per hour east
(D) 60 miles per hour south -
A ball is thrown into the air and falls back down. What is the force acting on the ball as it falls?
(A) The force of gravity
(B) The force of the air resistance
(C) The force of the thrower’s hand
(D) The force of the ground -
A hammer hits a nail. What is the impact of the hammer on the nail?
(A) The force of the hammer hitting the nail
(B) The Sound of the hammer hitting the nail
(C) The dent in the nail caused by the hammer
(D) The nail being driven into the wood -
A person lifts a heavy box. What is the work done by the person?
(A) The force of the person lifting the box
(B) The distance the person lifts the box
(C) The product of the force and the distance
(D) The energy used by the person to lift the box -
A light bulb is turned on. What is the power of the light bulb?
(A) The rate at which the light bulb converts electricity into light
(B) The amount of light produced by the light bulb
(C) The voltage of the light bulb
(D) The current of the light bulb -
A battery is used to power a toy car. What is the energy stored in the battery?
(A) The ability of the battery to do work
(B) The amount of charge in the battery
(C) The voltage of the battery
(D) The current of the battery -
A person is standing on a scale. What is the weight of the person?
(A) The force of gravity on the person
(B) The force of the scale on the person
(C) The mass of the person
(D) The acceleration of the person -
A car is moving at a constant speed of 60 miles per hour. What is the force of air resistance on the car?
(A) Zero
(B) The same as the force of gravity on the car
(C) Less than the force of gravity on the car
(D) More than the force of gravity on the car -
A ball is thrown into the air and falls back down. What is the change in the ball’s energy as it falls?
(A) The energy increases
(B) The energy decreases
(C) The energy remains the same -
A person lifts a heavy box. What is the change in the box’s energy?
(A) The energy increases
(B) The energy decreases
(C) The energy remains the same