Forces

Question 1

what is a vector quantity?

Answer 1

Have a magnitude (size) and direction e.g. 11m west. There are only six vector quantities: displacement, velocity, acceleration, force, weight and momentum.

Question 2

what is a scalar quantity?

Answer 2

Have only a magnitude (size) e.g. 11m. There are many different scalar quantities: speed, distance, time, power and energy are all scalar quantities.

Question 3

what is force?

Answer 3

A push or a pull that acts on an object due to its interaction with another object. All forces are measured in newtons.

Question 4

what is a contact force?

Answer 4

A force that occurs when two objects physically touch.

Question 5

what is a non contact force?

Answer 5

A force that occurs between two objects that are physically separated.

Question 6

what is a resultant force?

Answer 6

A force which is the result of two or more forces acting on an object.

Question 7

When all the forces are balanced, the resultant force is
zero. In this case:

Answer 7

a stationary object remains stationary
a moving object keeps on moving at the same
speed in the same direction

Question 8

When all the forces are not balanced, the resultant force is not zero. In this case:

Answer 8

A stationary object begins to move in the direction of the resultant force.
A moving object speeds up, slows down or changes direction depending on the direction of the resultant force

Question 9

how can the centre of mass be found on a symmetrical object?

Answer 9

The centre of mass for a symmetrical object can be found by marking the axes of symmetry on the object. The centre of mass is where the axes of symmetry cross.

Question 10

what is centre of mass?

Answer 10

Every particle in your body has a small gravitational force acting on it. Together, these forces act like a single force pulling at just one point. This single force is your weight. The point is called your centre of gravity or centre of mass.

Question 11

what is A scale diagram of two force vectors used to work out?

Answer 11

It is used to find the resultant of two forces that do not act along the same line.
The resultant is the diagonal that starts at the origin of the two forces. (parallelogram)

Question 12

how do you work out the resolution of forces?

Answer 12

Resolving a force means finding perpendicular components that have a resultant which is equal to the force. To resolve a force in two perpendicular directions, draw a rectangle with adjacent sides along the two directions so that the diagonal represents the force vector
(pythagorus)