Forces

Question 1

Newton’s First law

Answer 1

If the resultant force of an object is 0 :
1. if stationary, remain stationary
2. if moving, keep moving at a steady speed in the same direction (same velocity).

Question 2

Newton’s Second Law

Answer 2

the acceleration of an object is proportional to the resultant force acting on the object, and inversely proportional to the mass of the object.
F = Ma

Question 3

Newton’s Third Law

Answer 3

when two objects interact, the forces they exert on each other are equal and opposite. (every action has an equal and opposite reaction).

Question 4

Inertia

Answer 4

measure of how difficult it is to change velocity of an object

Question 5

Terminal velocity

Answer 5

Forces acting
resultant force
acceleration
change in velocity

Question 6

Resultant force

Answer 6

overall or net force acting on an object

Question 7

vector quantities

Answer 7

includes magnitude and direction
1. velocity
2. displacement
3. acceleration
4. force

Question 8

Scalar quantities

Answer 8

includes only magnitude
1. speed
2. distance
3. time
4. mass

Question 9

Force

Answer 9

a push or pull that acts on an object due to the interaction with another object.

Question 10

contact forces

Answer 10

Friction - sliding along surfaces
Lift - upward force on a wing
Thrust – propulsive force of an engine
Up thrust – upwards force when an object is in a fluid (boat)
Drag – acts against objects moving through a fluid
Tension - is described as a pulling force transmitted by a string or similar object
Normal contact force – push or pull

Question 11

non contact forces

Answer 11

Weight – force due to gravity
Magnetic – force between magnetic objects
Electrostatic – force between charged objects

Question 12

Weight

Answer 12

Weight (N) = mass (Kg) x gravitational field strength (N/Kg)
W = Mg

Question 13

Work

Answer 13

Work done (J) = force (J) x distance (m)
W = fs

Question 14

Hooke’s Law

Answer 14

force (N) = spring constant (N/m) x extension (m)
F = Ke
The extension of an object that obeys Hooke’s law is directly proportional to the force applied.

Question 15

Springs

Answer 15

Compression – the act of pressing something into a smaller space or putting pressure on it from different sides until it gets smaller.
Stretching – the act of pulling an object to enlarge the size.

An object is elastic if it returns to its original shape when the force is removed.
An object is elastically deformed if the object doesn’t return to its original shape when the force is removed.

Question 16

Pressure

Answer 16

pressure (Pa) = force (N) / area (m^2)
P = F / a

Question 17

distance

Answer 17

how far an object moves

Question 18

displacement

Answer 18

includes both the distance moved measured in a straight line and the direction of the line.

Question 19

Speed

Answer 19

speed (m/s) = distance (m) / time (s)
V = d / t

Question 20

average speeds

Answer 20

walking - 1.5 m/s
running - 3m/s
cycling - 6m/s

Question 21

Acceleration

Answer 21

Acceleration (m/s/s) = change in velocity (m/s) / time (s)

Question 22

SUVAT

Answer 22

final velocity^2 (m/s) = initial velocity^2 (m/s) + 2as
V^2 = u^2 + 2as

Question 23

kinetic potential energy

Answer 23

kinetic energy = 1/2 mass x velocity^2
Ek = 1/2 mv^2

Question 24

stopping distance

Answer 24

stopping distance = thinking distance + braking distance

Question 25

thinking distance

Answer 25

how far the car travels during the drivers reaction time
thinking distance = reaction time x speed

Question 26

braking distance

Answer 26

how far the car travels before coming to a stop, whilst the breaking force is applied