Unit 2, recap of year 9

Question 1

Efficiency formula

Answer 1

Efficiency = useful energy out / total energy in

Question 2

GPE (Gravitational Potential Energy)

Answer 2

GPE = m * g * h

Question 3

KE (Kinetic Energy)

Answer 3

KE = 1/2 * m * v^2

Question 3

Mass

Answer 3

Mass is the amount of matter in an object and is
measured in kilograms. Mass is not a force.

Question 4

Weight

Answer 4

Weight is a force and is caused by the pull of gravity
acting on a mass. Like other forces, weight is measured
in newtons and has both magnitude and direction.
Weight has different values depending on where
you are in the Universe.

Question 5

Weight formula

Answer 5

Weight = mass * g
N. kg. N/kg

Question 6

g = ?

Answer 6

g = 10 N/kg

Question 7

Newtons 1st Law

Answer 7

Newtons 1st Law
* An object at rest stays at rest…
* and an object in motion stays in motion with the same speed
and in the same direction…
* unless it is acted upon by an unbalanced force.
* Balanced forces= object keeps doing what its doing.
* Unbalanced forces= acceleration or deceleration.

Question 8

Momentum

Answer 8

Momentum is measure of the tendency of an object to keep moving - or of how hard it is to stop it moving. The momentum of an object depends on its mass and its velocity. Momentum depends on vector quantity ( velocity ), and is also a vector.

Question 9

Momentum formula

Answer 9

Momentum = mass * velocity
kg m/s. kg. m/s.

Question 10

Speed

Answer 10

Speed tells us how fast an object is moving.

Question 11

Speed formula

Answer 11

Speed = distance / time
m/s m. s

Question 12

Newton’s 2nd Law, formula

Answer 12

F = m * a
N. kg. m/s^2

Question 13

Newton’s Third Law

Answer 13

For every action, there is an equal and opposite reaction.