⭐️Topic SP8/SP9-Forces Doing Work And Their Effects Flashcards
What is work done?
The energy transferred by a force
How can you calculate work done?
Work done (J)= force (N) x distance moved in the direction if the force (m)
Danny is moving a box weighing 300N. He pulls in 3m along a skipping ramp using a force of 200N. Calculate the work done Danny does.
E (work done) = F (force) x d (distance)
= 200N x 3m
= 600J
What is power?
The rate at which energy is transferred
Power is also the rate of doing work…
When energy is being transferred by forces
What is power’s unit? What does this mean?
Watt (W) and 1 watt means 1 joule if work done per second
How can you calculate power?
Power (W) = work done (J) / time taken (s)
What is the force between two objects that are touching called?
Contact force
Name a pair of contact forces on a boat
The force from the engine and water resistance as the engine keeps the boat moving as water resistance slows it down
What kind of force is gravity?
A non-contact force
What are action reaction forces?
Pairs of forces acting on different objects in opposite directions
How does gravity work on the moon in respect to the earth?
It causes the two bodies to attract each other
What kind of force is the gravity that that hold the moon and the earth and acts in an opposite direction?
Action reaction force
What’s a force field?
The space around an object where it can affect others
Why do the moon and earth effect each other?
As the moon is within the earth’s gravitational field
Give examples of a force field?
- gravitational field
- magnetic field
- electrostatic field
What metals can a magnet attract?
Iron, nickel, colbat,
How does an electric field effect two objects within it that have the same charge and are close together
They produce a pair of forces in equal size and acting in opposite direction
What does it mean if a plane is flying at a constant velocity?
The horizontal and vertical forces on the plane are balanced
What can a scale diagram be used to find?
The resultant force
Give the steps to drawing a scale diagram in order to find the resultant force
- draw arrows at the correct angles to represent forces, length represents the size so you need a scale diagram
- draw lines to make a parallelogram
- the diagonal of the parallelogram is the resultant force and measure this to find the force
How can you use scale diagrams to resolve the forces?
- draw a force arrow to scale at the correct angle
- draw a rectangle with sides in directions you’re interested in
- measure the sides of the rectangle for the resolved forces
What is a moment?
A turning force
How can you find moment of a force?
Moment ( N m) = force x distance perpendicular to direction of the force
What’s the rule for when a system involving rotational forces is in equilibrium?
The sum of clockwise moments = sum of anti clockwise moments
What’s a lever?
A bar that pivots about a point and is used to transfer a force
What can gears do?
Transmit the rotational effect of a force
Gear X has 10 teeth and is connected to gear Y which has 40. How many times will gear X turn for Y?
4 times
Explain how the work is done when a ball is dropped and falls onto sand [2]
Work done displaces the sand [1] as kinetic energy from the ball has been transferred [1]
