Section 1

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Use of momentum in Newton's 2nd law

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Cards (46)

Section 1

(46 cards)

Use of momentum in Newton's 2nd law

Front

States that the resultant force is proportional to the rate of change of momentum F= (final momentum - initial momentum)/time

Back

Thermal capacity

Front

Two different objects with the same mass and energy input will have different temperature changes Energy required to raise an objects temperature by 1K C= Energy / change in temp

Back

Average speed

Front

distance travelled/total time taken for journey

Back

Ideal gas

Front

follows the gas laws for all values of P, V and T

Back

Percentage Uncertainties

Front

(Difference from average/average measurement) x 100

Back

Velocity-time graph

Front

The gradient of this graph shows the acceleration and the area under the graph shows the distance travelled

Back

Acceleration-time graph

Front

The area under graph gives the final velocity

Back

Description of a force

Front

should include Its magnitude Its direction the object on which it acts the object that exerts the force the nature of the force

Back

Newton's laws of motion

Front

1st law of motion- States that 'an object continues in uniform motion in a straight-line or at rest unless an external force acts on it' 2nd law of motion- 'Force = mass x acceleration (F=ma) This also means that the acceleration of an object - is proportional to the force applied - is inversely proportional to its mass also as mass is greater then the acceleration from the force will be smaller however if mass becomes smaller acceleration will become greater. 3rd law of motion- 'Every action has an equal opposite reaction' (e.g. when two bodies A and B interact, the force that is exerted on A is equal and opposite to the force that B exerts on A) There are some rules that apply to the 3rd law - the force are equal - the force acts on different bodies - the forces acts in opposite directions - the forces must both be the same type

Back

Types of energy and their equations

Front

Types: Kinetic energy= 1/2mv^2 Gravitational energy= mgh Elastic potential energy - spring constant, F= k.x - Elastic PE= 1/2F.x therefore = 1/2k.x^2 Thermal energy Chemical energy Internal energy Electrical energy

Back

Charles's law

Front

Vi / Ti = Vf / Tf where Pressure has to be constant

Back

Specific Latent heat

Front

amount of energy per unit mass absorbed or released during a change of state vaporisation = E= SHLV.M Fusion = E = SHLF.M

Back

Equations used for motion

Front

S= displacement or distance travelled U= initial velocity V= final velocity A= acceleration T= time taken

Back

Gas molecules

Front

1) molecules move randomly 2) there are no forces of attraction between molecules 3) the volume of the molecules is negligible 4) molecule collisions are elastic - no energy is lost

Back

Scalar measurements

Front

Mass (kg), Length (m), Time (s), Current (A), Temperature (K), Speed (m/s), Pressure (Pa), Potential difference (V), Resistance (ohms), Energy (J), Charge (C), Power (W), Frequency (Hz)

Back

Elastic and inelastic collisions

Front

A collision which no energy is lost is called an elastic collision A collision where a large amount of energy is lost through heat and sound however momentum is still conserved is called perfectly inelastic collision A collision where only some energy is lost however the total momentum still remains the same is called inelastic collision

Back

Conservation of Momentum

Front

'Momentum is always conserved if there are no other external force acting on the system' This means that when 2 masses interact momentum before interaction = momentum after interaction So, m.v1 + M.V1 = m.Vf + M.Vf

Back

Systematic error

Front

An error that occurs on all measurements that are caused by mostly instruments and apparatus used to measure data. Systematic error cannot be reduced by repeating experiments.

Back

Thermal energy in gases

Front

Temperature, volume and pressure are all interrelated

Back

To calculate mole

Front

n = N / NA

Back

Average velocity

Front

Distance travelled in a specific direction/time taken

Back

What is work

Front

Work is done when a force move its points of application in the direction of the force. However if the force moves at right angles to the direction of the force, then no work has been done. Work is define as if the force and the displacement are in the same direction, this can be simplified to 'Work done = force x distance'

Back

Latent Heat

Front

The amount of energy required to change an objects state L= E/M There are 2 types of latent heat Fusion - Changes solid to liquid Vaporisation - Changes liquid to gas Latent heat does not effect kinetic energy but effects potential energy (breaking and forming bonds)

Back

What can a force do

Front

A force causes a CHANGE in velocity, however if the force is zero this makes the velocity constant. A force causes acceleration.

Back

Vector measurements

Front

Force (N), Displacement (m), Acceleration (m/s2), Velocity (m/s)

Back

Instantaneous velocity

Front

The speed and direction at an instant in time

Back

Powers Uncertainties

Front

if y= a^n then the uncertainty would be n(difference from average/average measurement) (e.g. cube has 5cm +/- 5mm length % Uncertainty in length= 0.5/5= 10% Volume = (length)^3= 125cm^3 % Uncertainty in volume = 3 x (% uncertainty in length)= 3x10= 30% Absolute uncertainty= 30% of 125 =37.5 Volume of cube = 125 +/- 38cm^3)

Back

General gas equation

Front

P.V / T = R or p.v = n.R.T however the value of the constant depends on the amount of gas

Back

Specific heat capacity

Front

the energy required to raise a unit of mass by a temperature of 1k SHC = Energy / mass x change in temp = I.t.V / m(T2 - T1)

Back

Momentum

Front

The product of mass and velocity Momentum = mass x velocity p = mv Because velocity is a vector this makes momentum a vector.

Back

Power

Front

power is the amount of energy supplied per second; P= E/T Therefore it could be; P= W.D/t which equals P= F.D/t so power can also be measured by P= force x velocity

Back

Equilibrium

Front

If the resultant force on an object is zero then it is said to be in equilibrium An object could only be said to be in equilibrium when: - An object that is constantly at rest - An object that is moving with constant velocity in a straight line if in equilibrium T sin theta = P (since no resultant horizontal force) T cos theta = W (since no resultant vertical force)

Back

Absolute Uncertainties

Front

Difference between the average and the original values (e.g. 15.5cm +/- 5mm therefore the value must be between 15cm and 16cm) answer is 5mm

Back

Pressure law

Front

Pi / Vi = Pf / Vf where Volume has to be constant

Back

Distance-time graph

Front

The gradient of this graph shows the speed

Back

Friction

Front

There are 2 types of friction Static - The 2 surfaces have no relative motion Dynamic - The 2 surfaces are moving over each other Equations

Back

Instantaneous speed

Front

The speed at an instant in time

Back

Fractional Uncertainties

Front

Difference from average/average measurement

Back

Internal energy

Front

is the total random kinetic energy plus the potential energy that is stored by the chemical bonds between the molecules

Back

Different types of forces

Front

Gravitational force, Electrostatic force, Magnetic force, Normal reaction, Friction, Tension, Compression, Upthrust, Lift

Back

Acceleration

Front

is the change in velocity/time (acceleration due to gravity= 9.81m/s^2 since the gravitational force=9.81N)

Back

Boyle's Law

Front

Pi . Vi = Pf . Vf where Temperature has to be constant

Back

Impulse

Front

impulse is the result of change in momentum

Back

Thermal Equilibrium

Front

When 2 objects come in contact together, after a period of time they will reach the same temperature.

Back

Efficiency

Front

Is the measurement if the energy transferred is useful or not. Efficiency= useful work out/total energy in = useful power out/total power in

Back

Random error

Front

Is an unpredictable and largely uncontrollable uncertainty which are made by humans. Random uncertainties can be reduced by taking the average reading from the datas.

Back