Forces Revision
- Created by: Revisionforever2
- Created on: 02-06-20 15:29
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- Forces
- Vectors and Scalars
- Vectors - anything we can measure in science that has a direction.
- Velocity (speed in a given direction)
- acceleration force
- Scalars - something that can be measured without a direction.
- distance
- Speed
- mass
- Temperature
- Scalar quantities have size or magnitude but a directions is not specified (temperature, mass, speed etc)
- Scalars - something that can be measured without a direction.
- distance
- Speed
- mass
- Temperature
- Scalars - something that can be measured without a direction.
- Vector quantities have magnitude and a specific direction (velocity, acceleration etc.)
- Vectors - anything we can measure in science that has a direction.
- Contact and Non-Contact Forces
- Contact forces:Drag (air resistance) friction, tension, thrust
- Non-contact forces; static electricity, magnetism, gravity
- Contact Forces- if two objects touch each other to feel a force the forces are called contact forces.
- Non-contact forces- if two objects have/feel a force without touching, the forces are called non-contact forces
- Equal and opposite forces: forces always come in pairs, when you push against a wall, you feel the wall push back,
- In each pair of forces: the forces are equal sizes and opposite directions.
- Newton's Third Law: "When two objects interact with each other, they exert equal and opposite forces on each other.
- If you push or pull on something, you make a pair of forces, they are the same size and opposite directions.
- Forces: Work Done
- Balance and unbalance forces; Zero resultant forces is balanced forces , resultant forces bigger than zero are unbalanced forces.
- If the resultant force on an object is zero (balanced) then there is no change in speed or direction. If a resultant force is bigger than zero (unbalanced) then the speed and/or the direction of the object changes
- if the forces are balanced then the speed of the object will remain steady or stationery.
- If the forces are unbalanced then the speed of the object will accelerate or decelerate and/or change direction.
- To describe the effects of resultant forces you need to:1)calculate the resultant force and its direction. 2) Describe the effect, state whether the object accelerates/ decelerates or remains stationery. Then mention whether there is a change in direction or not
- Work done equals energy transferred. work done (Joules, J) = force (Newtons, N) x distance (metres, m)
- Wet Foxes Stink
- When you lift an object upwards, you are doing work against the force of gravity. This means the force used is the same as the weight of the object. The distance is the vertical height that the object moves.
- Parallelogram and resolution of forces
- Resultant force- a single force that has the effects of all forces acting on an object.
- Magnitude - the size of the force
- Gravity and Centre of Mass
- Weight is measured in newtons using a newton metre.
- Centre of mass- the weight of an object can be considered to act at a single point called the "centre of mass"
- For a symmetrical object the centre of mass is along the centre of symmetry.
- Gravity- weight is the force on an object due to gravity. The forces of gravity close to earth is due to the gravitational field around Earth. The weight of an object depends on the gravitational field strength at the point where the object is.
- Weight (Newtons, N) = mass (kg) x gravitational field strength (Newtons per kg, N/kg) worms munch garbage
- The weight of an object may be considered to act as a single point referred to as the objects of "centre mass". The weight of an object and the mass of an object are directly proportional.
- Extension of a Spring
- Directly proportional means that every time you add 1N of force the spring stretches the same amount.
- As you increase the spring constant the length of extension in mm, decreases.
- Hooke's Law: force (Newtons, N) = the spring constant (Newtons per m, N/m) x extension (metres, m) French Kangaroos Exist!
- The limit of proportionality is the point where the extension is no longer proportional to the force.
- Forces and Elasticity
- Inelastic deformation - when you overstretch a spring resulting in it showing an extension at 0 wights as it stretched too much previously.
- This means you have exceeded the limit if proportionality.
- Work done in stretching a spring: elastic potential energy (J)= 0.5 x spring constant (N/m) x extension squared (m)
- Forces that can act on an object are vectors, they have magnitude and direction.
- Elastic potential energy is the energy stores in anything that is stretched or squashed. The amount of energy stored depends on the extension of the object. The elastic potential energy also depends on spring constant, which tells us how easy or difficult it is to stretch the thing.
- Extension = new length - original length. Extension is measured in metres.
- Inelastic deformation - when you overstretch a spring resulting in it showing an extension at 0 wights as it stretched too much previously.
- Vectors and Scalars
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