Chapter 8 - Forces in balance

Question 1

Displacement

Answer 1

Distance travelled in a certain distance

Question 2

Distance

Answer 2

How far an object moves

Question 3

Vectors

Answer 3

Quantities that have both magnitude and a direction

Question 4

Scalers

Answer 4

Quantities that have magnitude, no direction.

Question 5

Examples of vectors (6)

Answer 5

Displacement, velocity, acceleration, force, weight, momentum

Question 6

Examples of scalers (4)

Answer 6

Mass, speed, time, distance

Question 7

Vectors shown through arrows

Answer 7

The direction of the arrow shows the direction of the vector, and the length of the arrow shows the magnitude of the vector

Question 8

Scale diagrams

Answer 8

A diagram is used to show when more than one force is acting upon an object.

Question 9

Force

Answer 9

A push or pull acting on an object because of an interaction with another object.

Question 10

Contact force

Answer 10

A force that is exerted only when 2 objects touch

Question 11

Non-contact force

Answer 11

A force that one object can apply to another object without touching it.

Question 12

Examples of contact forces (4)

Answer 12

Friction, air resistance, tension, normal contact force.

Question 13

Examples of non-contact force (3)

Answer 13

Gravitational forces, electrostatic forces, and magnetic forces.

Question 14

Newton’s third law of motion

Answer 14

When 2 objects interact with each other, they exert an equal and opposite force on each other.

Question 15

Driving force

Answer 15

The force of a vehicle that makes it move.

Question 16

Friction in cars

Answer 16

A car can only move forward due to the friction between the car and the ground. Friction only acts where the tyre is in contact with the ground

Question 17

Resultant force

Answer 17

A single force that has the same effect as all the forces acting on the object.

Question 18

Zeron resultant force

Answer 18

When all forces are balanced the object is stationary or travelling at a continuos speed.

Question 19

Newton’s first law of motion

Answer 19

An object at rest stays at rest and an object in motion stays in motion with the same speed and same direction unless acted upon by an unbalanced force.

Question 20

Unbalanced forces

Answer 20

Forces that cause a change in the motion of an object. The object’s movement depends on the size and direction of the resultant force.

Question 21

Free body diagram

Answer 21

A diagram that shows all the forces acting on an object.

Question 22

Calculating the resultant force.

Answer 22

The resultant force is equal to the difference between the forces and in the direction of the largest force.

Question 23

How to increase momentum

Answer 23

Increase the size of the force or increase the distance from pivot.

Question 24

The weight of an object is called?

Answer 24

A load

Question 25

The force applied to the lever is called?

Answer 25

Effort.

Question 26

Pivot

Answer 26

The point at which the lever turns.

Question 27

Examples of force multipliers.

Answer 27

Bottle openers and a pair of scissors.

Question 28

The line that a force acts along is called>

Answer 28

Line of action

Question 29

Force multiplier

Answer 29

A lever where the load is bigger than the effort.

Question 30

Gears

Answer 30

They act like levers as they multiply the effect of a turning force.

Question 31

How gears work.

Answer 31

Gear wheels exert an equal and opposite force on each other when their edges are in contact. The force of each gear acts perpendicular to the centre of the wheel

Question 32

Effects of sizes of gears

Answer 32

The turning force of a larger wheel acts further from the shaft than the turning force for a smaller gear. It means that the turning effect of the wheel shaft is bigger than the turning effect on the engine shaft

Question 33

Low gear

Answer 33

Low speed and high turning effect

Question 34

High gear

Answer 34

High speed and low turning effect

Question 35

Centre of mass

Answer 35

The point at which the mass of an object comes to rest and has no rotational forces when hanging. This is because the centre of mass is directly below then point of suspension.

Question 36

Identifying the centre of mass

Answer 36

If an object has more than one line of symmetry, the centre of mass is the pint at which the lines meet.

Question 37

Suspended equilibrium

Answer 37

The point at which an object comes to rest and has no rotational forces when hanging. This is because the centre of mass is directly below the point of suspension

Question 38

Principle of moments

Answer 38

The sum of all the clockwise moments about any point = the sum of all anticlockwise moments about the same point.

Question 39

A balanced seesaw

Answer 39

The monet of the left hand side must equal the moment of the right hand side for the seesaw to be balanced.

Question 40

Parallelogram of forces

Answer 40

A geometrical method is used to find the resultant force of two forces that don't act on the same line.

Question 41

How to create a parallelogram of forces.

Answer 41

Draw the vectors of the forces at the correct angles to each other. Using a compass, complete the parallelogram. Measure the distance from the starting point to the opposite point of the parallelogram and that is the resultant force

Question 42

Resolution of forces

Answer 42

The process of considering a force in terms of two perpendicular components, which together have the same effect on an object as the force

Question 43

Conditions for an object to be in equilibrium

Answer 43

There are zero resultant forces on the object and the forces acting on the object have no overall turning effect.

Question 44

Identifying an object in equilibrium when the lines of action of the forces are parallel

Answer 44

The sum of the forces in one direction must be equal to the sum of the forces in the other direction.

Question 45

Identifying an object in equilibrium when the lines of action of the forces are not parallel.

Answer 45

The forces can be resolved into 2 components along the same perpendicular line. These components must then balance out if the object is in equilibrium.