Topic 8&9-forces Doing Work And Their Affect Flashcards
(30 cards)
When is energy transferred and give an example?
Energy is transferred whenever things happen or when a force makes something move.
E.g electricity transfers energy to an electric light bulb, which then transfers every to surroundings by light and heat (thermal)
What does work done mean?
A measure of energy transferred when a force acs through a distance.
What does the amount of work done depend on?
The amount of energy transferred by a force is work done. The energy depends on the size of the force and how far the force has been moved.
What is the equation to work out work done?
Work done = force x distance
Can be written as
E = F x d
What are the units for the equation to work out word done?
Units for work done is: joules (J)
Force = Newtons (N)
Distance = (M)
What does power mean?
Power is the rate at which energy is transferred. When energy is being transferred by forces, then Powers is also the rate of doing work.
What is power measured in and what is it equivalent too?
Power is measured in watts.
1 watt = 1 joule of work done per second.
How can power be calculated?
Power(W) = work done(J)/time taken(s)
P = E/t
What is a contact force give an example?
Objects can interact with each other by exerting forces on each other. If the objects are touching, then the forces between the, are contact forces.
E.g When you stand on the floor, there is an upward force from the floor on you called the normal contact force.
What is a non contact force and can you give an example?
Non contact force is when forces occur with out objects touching/interacting.
E.g a boat is floating on water the upthrust from the water is balanced by a non contact force called gravity. Gravity does not need to touch the boat to give it weight. The upthrust and the weight are both acting on the same object.
Why does the moon stay in orbit around the earth?
Because the two bodies are attracting aching other. The force from the moon on the earth is the same as the force form the earth on the moon, but in the opposite direction. 🌍🌕 ➡️⬅️ ⬅️➡️
This is also an action reaction pair (Newton’s 3rd law)
How can gravity be defined?
A force that occurs between any two objects that have a mass.
How can the gravitational forces between two objects with mass be represented?
As vectors with arrows that show both the direction and magnitude.
What is a force field? How does this link to the earth and moon?
The space around an object where it can affect other objects.
The moon and earth affect each other because the moon is within the earths gravitational field and vice versa.
What non-direct forces affect objects?
Magnetism and static electricity(electric field)
What effect does magnetism/magnets have in objects?
A magnet can attract objects made from magnetic materials including iron, nickel and cobalt. A magnet can attract or repel another magnet. The space around a magnet where it can affect other materials is called a magnetic field.
What sort of field does static electricity have and how does this affect objects?
An object charged with static electricity has an eclectic field (electrostatic field) around it. The electric field can affect objects within it. Two objects with the same charge that are close to each other produce a pair of equal size forces acting in opposite directions.
When are forces balanced?
If the forces are equal in size but in opposite directions, the resultant forces (or net force) is zero. The forces on the object are said to be balanced.
What is a free body day diagram and what can it represent?
A diagram of of an object showing al, the forces acting upon it and the size and direction of forces.
A free body diagram for an aeroplane. The arrows represent force vectors. The direction of an arrow shows the direction of the force and the length of the arrow that represents its size. You can sketch this as a box.
How can you use a scale diagram?
You can find the resultant force using a scale diagram.
How do you draw a scale diagram to work out the resultant force?
- Draw arrows at the correct angles to represent the forces. The length of each arrow should represent the size of the force.
- Draw the lines to make a parallelogram
- The resultant force is the diagonal of the parallelogram. Measure the arrows to work out the size of the resultant force.
What is a moment?
A turning force/rotating force is called a moment.
What does the moment of a force depend on?
The size of the force and where the force is applied. The greater the force and the further it is applied from the pivot the greater the moment. The distance between the force and the pivot is measure at right angles to the direction of the force.
What is the unit for a moment?
Newton metres (Nm)
