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41 Cards in this Set
- Front
- Back
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Define Scalar and Vector quantities and give examples. |
Scalar: magnitude without direction - eg density and volume Vector: a quantity that has magnitude and direction - eg displacement, weight, acceleration. |
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Define Displacement, Velocity and acceleration. |
Displacement = net distance moved in a particular direction Velocity = speed in a given direction. Acceleration = gradient of a velocity time graph = change in velocity / time. |
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Define average speed and instantaneous speed. |
Instantaneous speed - speed measured between two point a very small time apart. Average speed = distance covered/ time taken |
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Define the Newton |
the net force which gives a mass of 1 kg an acceleration of 1 m/s/s |
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Define moment of a force. |
moment = force * perpendicular distance from pivot/axis/point |
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Define torque of a couple |
one of forces * perpendicular distance between forces. |
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Define work done by a force. |
work done = force * distance moved |
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Define the joule |
Energy required to move a weight of 1 N through a distance of 1m |
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define power as the rate of work done |
power = work done/ time power = energy/time |
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Define the watt |
1 joule per second |
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Define the terms stress and strain |
Stress = force/cross sectional area Strain = extension/ original length |
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Define the term Young modulus and ultimate tensile strength |
Young Modulus = stress/strain - young modulus is equal to the gradient from stress-strain graph Ultimate Tensile strength = maximum stress material can withstand before fracture |
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Define the term elastic deformation and plastic deformation. |
Elastic deformation - extension proportional to force Plastic deformation - Material does not return to original length when force is removed. |
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Define density |
Density = mass/volume |
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Define linear momentum |
product of mass and velocity |
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Define net force on a body |
rate of change of momentum |
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Define impulse of a force |
area under a force/time graph Change in momentum |
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Define a perfectly elastic collision |
a collision with no change/ loss of kinetic energy |
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Define inelastic collision |
total energy is conserved though some loss of kinetic energy. Magnitude of the impulse on each object is the same. |
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What is the principle of moments? |
Sum of clockwise moments is equal to the sum of anticlockwise moments for an object in equilibrium. |
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Describe an experiment to determine the acceleration of free fall g using a falling body. |
Measurements: height (distance) and time Instruments: stop watch/timer/clock Calculation: g=2s/t^2 g=2 G is an estimate as there is drag |
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Describe experiment to determine centre of gravity of an object.
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Suspend object from a point and then mark a vertical line on the object - plumb line Suspend object from another point and draw another plumb line Where lines intersect is the centre of gravity. |
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Describe an experiment to determine behaviour of springs. |
Measurement: original length, extension, mass Equipment: Micrometer/ vernier calliper for diameter of wire, Ruler/ metre rule to measure original length, travelling microscope for measuring extension. Newton meter / scales |
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Explain how experiments carried out by Galileo overturned Aristotle's ideas of motion |
Objects of different weights rolled own incline plane. Objects have same acceleration Objects hit ground at same time. |
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Explain how forces act in a fluid when an object falls through it. |
Drag makes time longer Drag proportional to speed^2 |
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Explain what a couple is. |
a pair of forces that tends to produce rotation only |
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what is the net force and net moment of an object in equilibrium? |
0 |
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What is f=ma? |
a special case of Newton's Second Law where the mass is constant and the rate of change of momentum can be expressed as mass * acceleration. |
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Why can there be a change in kinetic energy when momentum is conserved in the interaction between bodies'? |
changes in kinetic energy occur because not all collisions are perfectly elastic, some energy is lost in deformation, thermal changes etc... |
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Why can't f=ma be used for particles travelling at very high speeds? |
mass of object at high speeds increases meaning mass isn't constant to use f=ma |
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what are the factors that affect magnitude of the drag force? |
Area Speed/velocity surface shape Viscosity |
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what is the weight of an object? |
the gravitational force acting on the object |
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What is meant by centre of gravity? |
The point of an object where the entire weight of an object appears to act. |
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State the principle of conservation of energy. |
Energy cannot be created or destroyed. It can only be transferred into other forms. |
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Why is the efficiency of a device never 100%? |
some energy is lost in form of heat. |
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State Newtons 1st law. |
A body will remain at rest or continue to move with constant velocity unless acted upon by an unbalanced force. |
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State Newtons 2nd law. |
Force is proportional to rate of change of momentum and change in momentum takes place in the direction of the force, |
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State Newtons 3rd law. |
When one body exerts a force upon another, the other body exerts an equal and opposite force on the first body. |
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State the principle of conservation of energy. |
Total momentum is conserved. |
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What is the area under a force against time graph equal to? |
the impulse. Impulse = change in momentum |
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State Archimedes' Principle |
When a body is completely or partially immersed in a fluid, it experiences an upthrust equal to the weight of the fluid it has displaced. |
