Forces and motion Flashcards Preview

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Flashcards in Forces and motion Deck (33):
1

Acceleration

rate of change of velocity

2

Braking distance of a car

The distance travelled by the car after the brakes are applied until the car stops

3

Braking force

the frictional force applied by the road on the tyre (in the opposite direction to the motion of the vehicle, that brings the vehicle to rest)

4

Brittle

Has no plastic region — breaks at its elastic limit

5

Centre of Gravity

The point on the object where the total weight (appears) to act

6

Conditions for Mechanical Equilibrium

Resultant force = 0, Resultant torque = 0

7

Couple

Two equal but opposite forces acting along different lines

8

Density

Density = Mass/Volume

9

Displacement

A vector directed from initial position to final position having magnitude equal to the distance between those points

10

Ductile

Large plastic region - can be drawn into a wire

11

Elastic Limit

When exceeded, a permanent deformation will remain when the stress is removed

12

Hooke's Law

Extension is proportional to the force applied up to the limit of proportionality

13

Joule

When a force of 1N acts over a distance 1m in the direction of the force, then the work done is equal to 1 joule

14

Moment of a force

Moment = force x perpendicular distance from pivot

15

Newton

The force required to cause a mass of 1kg to have an acceleration of 1m/s^2

16

Plastic Deformation

The material does not return to its original length when the stress is removed

17

Power

Rate of work done

18

Pressure

Pressure = Force / Area

19

Principle of conservation of energy

Energy cannot be created or destroyed; it can only be transformed. Hence, the total energy of a system remains constant

20

Principle of moments

The sum of the clockwise moments must equal the sum of the anti-clockwise moments about any point in equilibrium

21

Resultant force

The vector sum of all the individual forces acting on a body

22

Stiff

A stiff material has a high/large Young Modulus

23

Stopping distance of a car

Thinking distance + Braking distance

24

Tensile Strain

Extension per unit original length

25

Tensile Stress

Tensile force per unit cross-sectional area perpendicular to the force

26

Strong

Can take a high (maximum) stress before breaking

27

Torque of a couple

One of forces x perpendicular distance between the forces

28

Thinking distance

The distance travelled by the car in the time taken by the driver to react

29

Vector quantity

A quantity with magnitude and direction

30

Velocity

Rate of change of displacement

31

Watt

the power used when 1 joule of work is done per second

32

Work done by a force

Force x distance moved in the direction of the force

33

Young Modulus

The ration of tensile stress to tensile strain when Hooke's Law is obeyed