Forces

Question 1

What happens to the velocity if the resultant force is zero (Newton’s first law)

Answer 1

It is at a constant speed

Question 2

What is Newton’s third law?

Answer 2

When two objects interact with each other they exert equal and opposite forces on each other

Question 3

Hooke’s law

Answer 3

Force applied= spring constant x extension

Question 4

What is a moment

Answer 4

The size of the force (moment) depends on the effort (force applied) and the perpendicular distance from the line of action of the force to the pivot (length of the lever)

Question 5

How to calculate the moment

Answer 5

Moment of force= force x perpendicular distance from line of action of force to the pivot

M = f x d
Nm = N x m

Question 6

Force equation (newton’s second law)

Answer 6

Force= mass x acceleration

Question 7

Scalar vs vector

Answer 7

Vector has a magnitude and direction, scalar just a magnitude

Question 8

Gravitational force

Answer 8

Gravity is the force of attraction between masses, weight is mass x gravity

Question 9

Resultant force

Answer 9

The single force with the same effect as each individual force acting on it
It means that energy is transferred and work is done

Question 10

Work done=

Answer 10

Force x distance

Question 11

How to find the resultant force of forces not in opposite directions

Answer 11

Draw all the forces acting on an object
Draw a straight line from the start of the first force to the end of the last
Measure length for magnitude and angle for direction
Can use Pythagoras

Question 12

Equilibrium

Answer 12

If the forces give a resultant force of 0

Question 13

Stretching, compressing and bending

Answer 13

Need more than one force
Elastically deformed if it can return to the same shape when the force is removed
Inelastically deformed if it can’t return
Work is done and energy transferred to elastic potential

Question 14

Force=

Answer 14

Spring constant x extension
Until the limit of proportionality when the graph starts to curve
Hooke’s law

Question 15

Elastic potential energy

Answer 15

Elastic potential energy = 1/2 spring constant x extension 2

Question 16

Moment

Answer 16

The turning effect of the force

Moment = force x perpendicular distance from line of action to action of the force

Question 17

Gears

Answer 17

Interlink so turning one causes another to turn in the opposite direction
Transmit the rotational effect from one place to the other
Force to larger gear has bigger moment

Question 18

Fluid pressure=

Answer 18

Force/Area

Question 19

Pressure in a liquid depends on

Answer 19

Depth and density

Pressure = depth x density x gravitational field strength

Question 20

What force is from objects in fluids

Answer 20

The pressure exerts a force in every direction
Pressure increases with depth
Causes an upwards resultant force (upthrust)
Upthrust= weight of fluid displaced

Question 21

How does an object float

Answer 21

If weight is less than upthrust

So there is an upwards resultant force

Question 22

Walking, running, cycling speeds

Answer 22

1.5 m/s
3 m/s
6 m/s

Question 23

Car, train, plane speeds

Answer 23

25 m/s
55 m/s
250 m/s

Question 24

What affects travel speed

Answer 24

Fitness, age, distance terrain

Question 25

What affects speed of sound

Answer 25

What they are travelling through

Question 26

Wind speed is affected by

Answer 26

Temperature, atmospheric pressure, buildings or structures

Question 27

Acceleration

Answer 27

Change in velocity divided by time

Question 28

Uniform acceleration

Answer 28

Constant acceleration

Question 29

Uniform acceleration equation

Answer 29

Final Velocity squared - initial velocity squared = 2 x acceleration x distance