# Mechanics

• Created by: dkoning00
• Created on: 30-04-17 14:38
Define Displacement
Distance travelled in a specified direction from a given starting point
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Describe the difference between mass and weight
Mass of an object is a measurement of the amount of matter it contains (same everywhere), weight of an object (on the Earth) is the gravitational force exerted by the Earth on the object
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What is the gravitational field strength?
The gravitational force exerted on a mass of 1kg - value of 9.81 N/kg near the Earth's surface
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On a displacement-time graph what does the gradient equal?
Velocity
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On a velocity time graph what are the gradient and area under the graph equal to?
Acceleration and displacement, respectively
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On an acceleration-time graph what is the area under the graph equal to?
Change of velocity
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What is momentum?
Vector quantity of the products of velocity and mass of an object
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Give Newton's first law of motion
An object will remain in a state of rest or continue to move with a constant velocity unless acted upon by a resultant external force
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Give Newton's second law of motion
The acceleration of a body of constant mass is proportional to the resultant force applied to it and in the direction of the resultant force
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Give Newton's third law of motion
If body A exerts a force on body B, body B exerts an equal and opposite force on body A
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What conditions do two forces need to have to be a Newton third law pair?
Equal magnitude, opposite direction, same type, acting over the same period of time with the same line of action and on two opposing bodies
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Define Newton's second law in terms of momentum
For an object of constant mass, the rate of change of linear momentum of said object will be proportional to the resultant force acting upon it and in the direction of the resultant force
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How do you fully define a force?
You need to state what is creating the force, what the force is acting on, the direction of the force, the type of force and the magnitude of the force
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Define equilibrium
A body is in equilibrium if, when acted on by a number of forces, the resultant force (in any direction) is zero
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State the Principle of conservation of linear momentum
In any interaction between bodies, linear momentum is conserved provided no resultant external force acts
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Define Impulse giving its units
The change in momentum of a body caused by a resultant force (unit = Ns)
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How do you find Impulse on a Force-time graph?
Area under the graph
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How do you calculate parameters of projectile motion?
Break motion down into horizontal and vertical components then apply suvat equations separately
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What are Free-body force diagrams?
Diagrams showing the forces acting on one object with proportional lines in specific directions
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What is a centre of gravity?
The point at which all the weight of a complex shaped body can be considered to act
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What is a moment of a force?
The product of the force and the perpendicular distance between the axis of rotation and the line of action of the force
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State the principle of moments
If a system is in equilibrium, the sum of the clockwise moments must equal the sum of the anticlockwise moments about any point
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State the principle of conservation of energy
Energy cannot be created or destroyed, it can only be transferred from one form to another
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What is Kinetic Energy? Give the formula
Energy due to motion and given by: KE = ½ m v^2
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What is Change in Gravitational Potential Energy? Give the formula
GPE is the energy stored by an object due to its position (height). The Formula for finding the g.p.e. transferred close to the Earth’s surface is GPE = m g ∆h
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Explain Work/Work done and give the formula
Work is done on an object when a force is used to transfer energy to it. Work done = force × distance moved in direction of force
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What is Power? Give the formula
The rate at which work is done. Power = work done divided by time taken
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Give the formula for efficiency
Useful energy output divided by total energy input x 100
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## Other cards in this set

### Card 2

#### Front

Describe the difference between mass and weight

#### Back

Mass of an object is a measurement of the amount of matter it contains (same everywhere), weight of an object (on the Earth) is the gravitational force exerted by the Earth on the object

### Card 3

#### Front

What is the gravitational field strength?

### Card 4

#### Front

On a displacement-time graph what does the gradient equal?

### Card 5

#### Front

On a velocity time graph what are the gradient and area under the graph equal to?

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