Topic D- Dynamics

Question 1

what does Newton’s first Law sate?

Answer 1

An object will remain stationary or move at a constant velocity unless acted by a resultant force.

Question 2

What does Newton’s Second Law State?

Answer 2

when an resultant force acts on an object the object will accelerate. this is directly proportional to force and inversely proportional to mass.

Question 3

What is the equation under newtons second Law?

Answer 3

F = m a

Question 4

What does Newton’s Third Law State?

Answer 4

When 2 objects interact, they apply forces on one and another that are equal in magnitude and opposite in direction.

Question 5

What are the outcomes in newton’s third Law?

Answer 5

1) equal in size
2) opposite in direction
3) always acts on two different objects.

Question 6

what is mass?

Answer 6

mass is the amount of matter in a material. it is measured in kg.

Question 7

what is weight?

Answer 7

weight is a measure of how strong the gravitational force is acting on a specific mass. weight is a force, hence it is measured in newtons.

Question 8

Equation fir weight and mass?

Answer 8

w = m g

Question 9

what is the definition of newton?

Answer 9

1N is the force exerted on 1kg of mass when accelerated in 1ms^-2.

Question 10

what is friction?

Answer 10

friction is the force that opposes the relative movement of 2 surfaces.

it can be solid surfaces, liquid surfaces or gas surfaces.

Question 11

friction is always ______________ to the movement.

Answer 11

opposite.

Question 12

what is the drag force?

Answer 12

any object moving through a fluid experiences a force that opposes its movement. this opposing force is known as drag force.
EX: air resistance, water resistance.

Question 13

what does drag force depend on?

Answer 13

speed of the object. ( higher the speed higher the drag force)

shape of the object ( higher surface area higher the drag force )

Question 14

what is terminal velocity?

Answer 14

look at the Album

Question 15

what is momentum? what is it indicated with?

Answer 15

indicated with (P)
momentum is a vector, its direction is the same as the velocities direction.

Question 16

what is the equation of moment?

Answer 16

p = mv

f = mv-mu/t

Question 17

what is the equation of impulse?

Answer 17

impulse = f x t

impulse = mv - mu

Question 18

what is the principal of linear momentum conservation?

Answer 18

when there is no external force acting on a system, the total initial momentum is equal to the total final momentum.

Question 19

what is the equation of linear momentum conservation?

Answer 19

m1u1 + m2 u2 = m1 v1 + m2 v2
( if the velocity is opposite direction add a “-“ sign.

Question 20

what is kinetic energy?

Answer 20

the energy of an object due to it’s motion.

Question 21

what is the equation of KE?

Answer 21

KE = 1/2 * mv^2

Question 22

what elastic collision?

Answer 22

in elastic collision kinetic energy is the same before and after the collision. in other words there is no loss of kinetic energy.

Question 23

what is in- elastic collision?

Answer 23

in - elastic collision is when kinetic energy is less after the collision.

Question 24

what is energy?

Answer 24

energy is the ability to do work.

Question 25

name some energy stores

Answer 25

1) gravitational potential energy stores.
2) kinetic energy stores
3) thermal energy stores
4) elastic energy stores

Question 26

what is gravitational potential energy?

Answer 26

it is the energy of an object due to it’s position in the gravitational field.

Question 27

what is the equation of gravitational potential energy?

Answer 27

GPE = m . g . h

Question 28

what is the principal of conservation of energy?

Answer 28

energy cannot be created or destroyed.

Question 29

State an example for principal of conservation of energy.

Answer 29

ex: lets look at a simple pendulum, the total energy will be the same everywhere according to the principal of conservation of energy. but the energy transforms from kinetic and energy to GPE to kinetic again and so on…

(remember the diagram)

Question 30

what is power?

Answer 30

power is the energy transferred.

Question 31

what is the equation of power?

Answer 31

p = ΔE / ΔT

Question 32

what are the equations for efficiency?

Answer 32

efficiency = useful output power / total
input power x 100%

or

efficiency = useful work done / total work
done x 100%

Question 33

what is center of mass?

Answer 33

center of mass is called the center of gravity. it is a hypothetical point from where weight of an object acts.

Question 34

what is center of mass?

Answer 34

center of mass is called the center of gravity. it is a hypothetical point from where weight of an object acts.

Question 35

what is another term for turning effects?

Answer 35

moment of force

Question 36

What is the equation for moment of force?

Answer 36

moment = force x perpendicular distance between pivot and forces.

Question 36

what is the principal of moments?

Answer 36

sum of clockwise moments = sum of anti clock wise moments.

Question 37

what is a moment of a couple?

Answer 37

it is two equal and opposite forces acting on an object but not on the same line.

Question 38

what is the equation of moment of a couple?

Answer 38

force x distance between the forces.

Question 39

what are the conditions for an object to be at equilibrium?

Answer 39

1) resultant force has to be 0
2) at any point all clockwise moments must
be equal to all the anti clockwise
moments.

Question 40

what is stable equilibrium?

Answer 40

If an object is in stable equilibrium then when it is displaced and released from its equilibrium position it will return to its equilibrium position.
(it may wobble a little but it will return to its equilibrium position)

Question 41

what is unstable equilibrium?

Answer 41

if an object is in unstable equilibrium, then when it is displaced from its equilibrium position and released it will fall/ roll off.