Momentum, Impulse, Work, Energy And Power

Question 1

Linear momentum

Answer 1

the product of the mass and velocity of the object.

Question 2

Newton’s second law in terms of momentum

Answer 2

the net force acting on an object is equal to the rate of change of momentum.

Question 3

Isolated systems

Answer 3

a system where no net external forces acts on the system / a system where no energy gains or losses occur.

Question 4

Internal and external forces

Answer 4

Internal - forces exerted by the objects in the system on each other.
External - forces exerted on the system.

Question 5

Law of conservation of linear momentum

Answer 5

the total linear momentum of an isolated system remains constant (is conserved).

Question 6

Elastic collision

Answer 6

a collision in which both momentum and kinetic energy are conserved.

Question 7

Inelastic collision

Answer 7

a collision in which only momentum is conserved.

Question 8

Impulse

Answer 8

the product of the net force and the contact time.

Question 9

Work

Answer 9

the product of the displacement and the component of the force parallel to the displacement.

Question 10

“Wasted work”

Answer 10

the work done against friction.

Wwasted = Wfriction = fkΔx

Question 11

“Useful work”

Answer 11

work done by the net force to accelerate the object.

Wuseful = FresΔx

Wapplied force = Wuseful + Wwasted + Wgravity

Question 12

Potential energy

Answer 12

stored energy.

E.g. chemical potential energy, spring potential energy, gravitational potential energy, light energy

Question 13

Gravitational potential energy

Answer 13

the energy an object possesses due to its position relative to a reference point.

Question 14

Kinetic energy

Answer 14

the energy an object has as a result of the object’s motion.

E.g. sound energy, heat energy

Question 15

Mechanical energy

Answer 15

the sum of gravitational potential and kinetic energy at a point.

Question 16

Law of conservation of energy

Answer 16

the total energy in a system cannot be created nor destroyed: only transformed from one form to another.

Question 17

Principle of conservation of mechanical energy

Answer 17

in the absence of air resistance or any external forces, the mechanical energy of an object is constant.

Question 18

Transformation

Answer 18

one type of energy changes to another type of energy.

Question 19

Transfer

Answer 19

energy is passed from one object or system to another.

Question 20

Conservative force

Answer 20

a force in which the work done is independent of the path taken.

E.g. electrostatic force, elastic force in spring

Question 21

Non-conservative force

Answer 21

a force in which the work done in moving an object between two points depends on the path taken.

E.g. friction, air resistance, tension

Question 22

Work-energy theorem

Answer 22

the work done by a net force on an object is equal to the change in the kinetic energy of the object.

Question 23

Power

Answer 23

the rate at which work is done or the rate at which energy is transferred.

Question 24

Watt

Answer 24

one watt is defined as the power when one joule of work is done in one second.

Question 25

Efficiency

Answer 25

the ratio of output power to input power.