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Flashcards in Forces And Their Effects Deck (30)
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1

What is the resultant force?

When a number of forces acting at a point, they may be replaces by a single force that has the same effects on the motion as the original forces all acting together. This single force is called the resultant force.

2

What may a resultant force acting on an object cause?

A change in its state of rest or motion

3

If the resultant force acting on a stationary object is zero:

The object will remain stationary

4

If the resultant force acting on a stationary object is not zero:

The object will accelerate in the direction of the resultant force

5

If the resultant force acting on a moving object is zero:

The object will co tune to move in the same speed and in the same direction

6

If the resultant force acting on a moving object is not zero:

The object will accelerate in the direction of the resultant force

7

F (force) = m (mass) x a (acceleration)
What are the measures in?

Force-N
Mass-Kg
Acceleration-m/s^2

8

What does the gradient of a distance-time graph represent?

Speed

9

Who do you work out the speed of something?

Speed = distance/time

10

a (acceleration) = v (velocity) - u (initial velocity)/t (time)
What are they measured in?

a-m/s^2
v and u-m/s
T-seconds

11

What does the gradient Ina velocity-time graph show?

Acceleration

12

How do you calculate the distance travelled by the object from a velocity-time graph?

The area under the graph

13

What are most resistive forces cased by?

Air resistance

14

What is resistive force?

It ia a force acting a glints the object or another force

15

The greater the speed of the vehicle the....bedded to stop it in a certain direction

Greater the breaking force

16

How do you work out the stopping distance of a vehicle?

It is the sum of the distance the vehicle travels during the driver' see action time (thinking time) and the distance it travels under the breaking force (breaking distance

17

What may the drivers reaction time be affected by?

Tiredness
Drugs
Alcohol

18

Hat happens when the breaks are applied in a vehicle?

Work done by friction force between the brakes and the wheel reduces the kinetic energy of the vehicle and the temperature of the breaks increases

19

What may the vehicle's braking distance be affected by?

Adverse (poor) road - wet or icy conditions
Weather conditions - rain
Poor condition of the vehicle - car's brakes or tyres

20

The faster an object moves through a fluid the greater...

The frictional force that acts on it

21

What will happen to an object falling through a fluid?

It will initially accelerate due to the force of gravity. Eventually the resultant force will be zero and the object will move at its terminal velocity (steady speed)

22

Why does the use of a parachute reduce the parachutists terminal velocity?

The persons increases in velocity due to gravity
As they accelerate the frictional force (air resistance) also increase, in order to balance each other out
This causes the resultant force to reach zero
Which as a result allows the person to reach the terminal velocity and land safely onto the ground

23

W (weight) = m (mass) x g (gravitational field strength)
What are these measured in?

W - N
M - Kg
G - N/Kg (always 10)

24

What may the force on an object cause?

A change in shape of the object

25

What will happen when a force is applied to an elastic object, such as a spring?

It will result in the object stretching and storing elastic potential energy

26

What happens to an object that is able to recover its original shape?

Elastic potential energy is stored in the object when work is done on the object to change its shape

27

F (force) = k (spring constant) x e (extension)
What is each one measured in?

F - N
K - N/m
E - m

28

What happens whenever two objects interact?

The force they exert on each other are equal and opposite

29

What is velocity?

It is speed in a given direction

30

What happens when a vehicle is travelling at a constant speed?

The resistive forces (force acting against it) balance the driving force