GCSE Chapter 8 Revision Flashcards
8.1 Definition of displacement
Distance without change of direction.
8.1 definition of vectors
Physical quantities that have direction. Examples are acceleration, force, momentum, weight and gravitational field strength.
HAS MAGNITUDE AND DIRECTION
8.1 definition of scalars
Physical quantities that have size. Examples are speed, distance, time, mass, energy and power. Has MAGNITUDE only no direction
8.1 Definition of magnitude
Size of quantity. Example is that a vector has magnitude (i.e. size) as well as direction.
Example in an exam 5km east
8.1 To show direction of a vector quantity…
An arrow show this and the length of the arrow represents the magnitude of the vector quantity.
8.2 What do forces do?
Force changes the shape of an object or change its state of rest or its motion.
8.2 Two types of forces
Push or pull force
8.2 Newton’s third law of motion
When two objects interact with each other, they exert equal and opposite forces on each other.
Example: Boxer who punches 100N has an opposite force of 100N
8.2 What is a driving force
Force that makes a car move.
8.3 What is a resultant force?
Force that has the same effect as all the forces acting on the object.
When two or more forces act on an object, the resultant force can be found by adding up the individual forces.
Sum effect of more than one force
8.3 Newton’s first law of motion
A force acting on an object are balanced, the resultant force on the object is zero. These are called balanced forces.
8.3 What is an unbalanced force?
This is when the resultant force is not zero.
8.4 What is a moment?
It is the turning effect of a force.
It can be increased by: increasing the size of force and using a spanner with a longer handle.
8.4 What is a lever
An example of a force multiplier as the effort moves a much bigger load.
8.4 Meaning of load
Weight of an object.
8.4 Meaning of effort
Force of a person
8.4 formula of moment
Moment(Nm) = force(N) x perpendicular distance(m)
8.5 What are levers are used for
Increase the size of a force acting on an object or to make the object turn more easily. The force applied to the lever must act further from the pivot than the force it has to overcome.
8.5 What are gears?
Gears are like levers as they can multiply the effect of a turning force.
An example is when a car is low in gear, a small gear wheel turns a larger gear wheel.
Rotating wheels with teeth that interlock with other teeth. Use cogs.
8.5 What does a low gear mean?
It will give low speed and a high turning effect
8.5 What does a high gear mean?
High gear gives high speed and a low turning effect.
8.6 What is the centre of mass?
The centre of mass of an object is the point at which its mass can be thought as being concentrated.
8.6. What is Suspended equilibrium?
If you suspend an object and then release it, it will be sooner or later come to rest with its centre of mass directly below the point of suspension.
8.6 How do you find the centre of mass of a symmetrical object?
The centre of mass is where the axes of symmetry meet.
8.7 What are two types of movements in a moment
Clockwise and anticlockwise.
8.7 Formula of anticlockwise moment=clockwise moment
W1d1=W2d2
8.7 Principle of moments
The sum of all the clockwise moments about any point = the sum of all the anticlockwise moments about that point
8.8 How do you do the parallelogram of forces method?
Draw a line in the middle and measure the two angles on it. Next draw the Newtons (do a key 1cm = 1N). Next you do two parallel lines where the line has ended. Next draw a line of the opposite angle and its distance. Finally, from the other point join the line.
Connect the starting point and measure the angle and length (newton)
8.9 What does resolving a force mean?
Rewolving force means finding perpendicular components that have a resultant force that is equal to the force.
In the diagrams, there is an object and slope, draw a line and the weight. This means you can draw a rectangle.
8.9 Conditions of an equilibrium
Moment is 0
Or no overall turning effect.
8.9 How is an object at rest considered to be at an equilibrium?
The resultant force is zero so it is in equilibrium
8.3 What happens when the resultant force is a) 0 b) greater than zero
A) The object stays at rest or at the same speed or direction
B) Greater than zero, the speed or direction of an object will change.
