Physics - Year 10

SI unit of Length

Meter (m)

SI unit of Mass

Kg

SI unit of Time

Second (s)

SI unit of Temperature

Kelvin (K)

SI unit of amount of substance

Mole (mol)

Unit of Energy

Joules (J)

Unit of Force

Newton (N)

Unit of Pressure

Pascal (Pa)

Units for Frequency (pitch)

Hertz (Hz)

Unit of Loudness (amplitude)

Decibel (Db)

What is a random/human error?

It may be due to human error (in reaction speed or correct timing/measurement), a faulty technique, or faulty equipment.

What is a systematic error?

It is when the errors cause readings to be shifted one way or another from the true reading. It will usually be due to an error in the calibration/accuracy of equipment.

What is parallax error?

The measurement is not taken at eye level when trying to read it.

What is an anomalous result?

An anomalous result is one which is inconsistent to the others. Best way to identify is through a graph.

Accuracy

Involves how close you are to the correct result. How close a value is to the overall total value.

What error effects accuracy?

Systematic error

Precision

Is how consistently you can get that result using the same method. How close the experimental values are to each other.

What error effects precision?

Random error

Distance

The total movement of an object without any regards to direction.

Unit = meter (m)

Displacement

Change in position of an object. Shortest distance between two points in a particular direction.

Unit = meter (m)

Scalar quantity

Quantities that only have magnitude (or size)

Vector quantity

Quantities that have magnitude and direction.

Speed

The rate at which an object covers distance over time.

Unit = m/s

Velocity

The speed and direction of an objects movement. Measurement of the rate and direction of movement.

Unit = m/s

Speed =

Distance/Time

Velocity =

Displacement/Time

Acceleration

When velocity changes we have acceleration. Acceleration is defined as the rate of change of velocity over time. If the direction or speed changes, then there is a change in velocity, hence, acceleration is present.

Acceleration =

Change in velocity/Time

Gradient in Distance-Time Graph =

Speed

Distance-Time Graph: What is a flat section?

Object is at rest. Speed is 0.

Distance-Time Graph: What if the graph gets steeper?

The speed is increasing at that point in time.

Distance-Time Graph: What does a curve represent?

Acceleration

Curve getting steeper = speeding up

Curve leveling off = slowing down

Gradient in Velocity-Time Graph =

Acceleration

Velocity-Time Graph: What is a flat section?

Steady Speed/velocity

Velocity-Time Graph: What if the graph gets steeper?

Acceleration increases (steadily)

(or deceleration takes place)

Velocity-Time Graph: What does a curve represent?

Increasing/Decreasing Acceleration (changing acceleration)

Velocity-Time Graph: Area under the graph =

Displacement (If speed-time graph then it is distance)

Velocity-Time Graph: How to find speed?

Read value found on the Velocity axis.

Stopping Distance

The total distance a vehicle travels from the moment the driver realizes they need to stop until the vehicle comes to a complete stop. Sum of Thinking distance and Braking distance.

Thinking Distance

The distance the vehicle travels while the driver reacts and begins to apply the breaks

Braking Distance

The distance a vehicle travels after the breaks are applied until it stops.

Formula for Stoping Distance =

(u1)(t1) + ((u1)(t2))/2

u = initial velocity

t1 is the reaction time

t2 is the time after breaks

Factors affecting a person’s reaction time:

• Age

• Alcohol

• Distractions

• Medication

• Tiredness

Factors affecting the breaking distance:

• Mass of car

• Speed of car

• Car condition

• Road condition

Newton’s 1st Law:

Law of Inertia:
An object at rest remains at rest, or if in motion, remains in motion at a constant velocity unless acted upon by an unbalanced force.

Newton’s 2nd Law:

Law of Acceleration:

F = ma. The acceleration of the body is directly proportional to the net force acting on the body and inversely proportional to the mass of the body.

Newton’s 3rd Law:

Law of action and reaction:

For every action in nature, there is an equal and opposite reaction. Whenever two objects interact, they exert equal and opposite forces on each other.

Energy

The capacity or ability to do work.

Unit = Joules (J)

Work Done

Measure of energy transfer that occurs when an object is moved over a distance by an external force. The force is parallel to the displacement.

Unit = Joules (J)

Formula for Work Done =

Force x Distance (in direction of force)

Law of conservation of energy:

Energy can neither be created nor be destroyed. It can only be transformed/transferred from one form to another.

Heat/Thermal Energy

Energy based on temperature of an object.

Light Energy

Light emitted from an object.

Chemical Energy

Energy held in chemical bonds. Energy released when a substance undergoes a chemical reaction.

EXAMPLE: Batteries, Wood, Food, Petroleum, Natural Gas

Elastic Energy

Energy held in an already-stretched spring. A result of applying a force to deform an elastic object.

EXAMPLE: Springs, Rubber bands

Nuclear Energy

From breaking atoms apart. Energy released from the nucleus of an atom.

Magnetic Energy

Energy of magnetic forces and attraction from the use of magnets and magnetic fields.

EXAMPLE: Electric motors, generators, loudspeakers

Electrical Energy

Resulting from moving electric charges. Energy derived from electrical potential energy. Can be through sockets.

EXAMPLE: Lightning, Electric eel, Vacuum, TV, Kettle

Sound Energy

Energy stored in a sound wave. Any sound.

Kinetic Energy

Energy of a moving object. Depends on the mass of the object and the speed of the object.

EXAMPLE: A person walking/running, a ball thrown, charged particle.

Kinetic Energy Formula =

KE = ½ x m x v²

KE (Kinetic energy) = J

m (mass) = Kg

v (velocity) = m/s

If the mass of an object increases, what happens to its kinetic energy?

The kinetic energy of the object will increase.

Gravitational Potential Energy

Energy an object stores due to its height above the ground. The higher up, the more potential energy. Depends on the mass of object, height above surface, and the gravitational field strength.

Gravitational Potential Energy Formula =

GPE = m x g x h

GPE (Gravitational Potential Energy) = J

m (mass) = Kg

g (gravity) = N

h (height) = m

In order to achieve gravitational potential energy store, you must use ___ or ___ to overcome gravitational force/weight.

energy or work

Weight =

mass x gravity

What is the value of gravitational force?

9.81 m/s²

1 tonne = __ Kg

1000 Kg

1 Kg = __ tonnes

0.001 tonnes

Methods of Energy Transfer:

• Electrically

• Heating (temperature difference cause electrically or by chemical reaction)

• Mechanical (if you exert force on an object, a force moving an object through a distance)

• Sound

• Radiation (energy transferred as a wave)

Open System

Interacts with the outside world, can loose or gain energy, matter can or energy can leave.

Closed System

Does not interact with the outside world, can only loose or gain energy.

Energy Transferred =

= Work Done

Mechanical vs. Electrical Energy

Mechanical = Force to move an object, an energy causing motion.

Electrical = When current flows, energy required to overcome the resistance in the wires.

Energy Stores

Is the ability to capture energy at one time for use at a later time. Energy can be stored in many forms.

What happens when an object is falling?

The energy of the object gets transferred from its gravitational potential energy store to its kinetic energy store (if there is no air resistance)

In the absence of friction or air resistance, energy is ___ . The energy will not be lost or created.

energy is conserved

Total energy of the system is the:

sum of kinetic and potential energy.

If an object is falling and air resistance is present:

The energy will not only be transferred from its gravitational potential energy store to the kinetic energy store, but the energy will also be transferred and lost to other stores/ to the surroundings.

Energy dissipation =

= wasted energy or energy that is lost to the surroundings.

When a force of 1N moves an object by 1m, then 1J of work is done.

Work unit can also be Newton-meter (Nm)

1 Newton-meter of work = 1 Joule

Contact Forces:

• Frictional Force

• Tension Force

• Normal Force = force exerted on an object that is in contact with another stable object.

• Air-resistance Force

• Applied Force = force applied to an object by a person or another object.

• Spring Force = force of a compressed or stretched spring upon any object attached.

Non-Contact Forces:

• Gravitational Force/Weight = (w = mg)

• Electrical Force

• Magnetic Force

Power

Energy spend over time. Power is the rate at which energy is transferred or the rate at which work is done.

Unit = Watts (W)

Formula of Power =

energy transferred or change in energy (J) / time (s)

or

work done (J)/ time (s)

During free fall, mass is irrelevant …

as acceleration is constant

Efficiency

Is the proportions of the energy supplied transferred into the useful energy output.

Formula for Efficiency =

useful energy output / total energy input

or

useful power output / total power input