P10 - Forces and Motion

Question 1

What is Newton’s First Law?

Answer 1

If the resultant force acting on an stationary object is zero, then the object will remain still. If the resultant force acting on a moving object is zero, the object will continue moving at a constant speed

Question 2

What is Newton’s Second Law?

Answer 2

Force = Mass x Acceleration
F = m a
(N) (kg) (m/s²)

Question 3

What is Newton’s Third Law?

Answer 3

When 2 objects interact, the forces they exert on each other are equal in magnitude and opposite in direction

Question 4

What is the inertia?

Answer 4

The tendency of an object to stay at rest or to continue at a constant speed

Question 5

What is the inertial mass?

Answer 5

A measure of how difficult it is to change an object’s velocity

Question 6

What is the resultant force needed for?

Answer 6

To change an object’s velocity

Question 7

What does a low inertial mass mean for an object?

Answer 7

That it is easy to change it’s velocity (start moving and slow down)

Question 8

What does a high inertial mass mean for an object?

Answer 8

That it is hard to change it’s velocity (start moving and slow down)

Question 9

What is mass?

Answer 9

The measure of physical mass an object is comprised of

Question 10

What is weight?

Answer 10

The force acting on a mass due to gravity

Question 11

How do you alter an object’s weight?

Answer 11

By altering the gravitational field strength

Question 12

What is the equation for weight?

Answer 12

Weight = Mass x gravitational field strength
W = m x g
(N) (kg) (N/kg) or (m/s²)

Question 13

When you drop an object, why does it fall?

Answer 13

Because of it’s weight. No other forces act on it so the resultant force is the weight. The object accelerates at whatever the measurement of gravity is (9.8N/kg on Earth)

Question 14

If an object falls in a fluid then…

Answer 14

The fluid drags on the object due to friction between the fluid and surface of the object. The acceleration of the object decreases as it falls because the frictional force increases as the objects speeds up.

Question 15

What is the thinking distance?

Answer 15

The distance the vehicle goes in the time it takes the driver to apply the brakes after realising they need to stop

Question 16

What is the braking distance?

Answer 16

The distance the vehicle travels from when the brakes are first applied to when it completely stops

Question 17

What factors affect thinking distance?

Answer 17

Age
Alcohol
Drugs
Speed
Tiredness

Question 18

What factors affect braking distance?

Answer 18

Footwear
Type of car
Location of car
Type of road/ surface
Weather
Speed

Question 19

What is the total stopping distance?

Answer 19

The thinking distance + braking distance

Question 20

What does an object’s momentum tell us?

Answer 20

How difficult it will be to stop it moving

Question 21

What is the equation for momentum?

Answer 21

Momentum = Mass x Velocity
P = m x v
(kgm/s) (kg) (m/s)

Question 22

What is the Law of Conservation of Momentum?

Answer 22

In a closed system, the total momentum of an object is the same before and after collision

Question 23

What is the equation to find Force from Momentum and Time

Answer 23

Force = Δ Momentum ÷ Δ Time
F = ΔP ÷ Δt
(N) (Kgm/s) (s)

Question 24

What is the impulse?

Answer 24

A force acting for a length of time

Question 25

What is the equation for impulse?

Answer 25

Δ Momentum = Force x Δ Time
ΔP = F x ΔT
(Kgm/s) (N) (s)

Question 26

What is Hooke’s Law?

Answer 26

The extension of an object is directly proportional to the force that is applied to it provided that the limit of proportionality is not exceeded

Question 27

What happens to an object if its limit of proportionality is exceeded?

Answer 27

The object will snap/break

Question 28

What is the equation associated with Hooke’s Law?

Answer 28

Force = Spring Constant x Extension
F = k x e
(N) (N/m) (m)

Question 29

What is the practical for Hooke’s Law?

Answer 29

• Attach the spring to the clamp and let it hang freely
• Attach/hold a ruler vertically next to the spring
• Measure length of spring with no force acting on it
• Hang mass on the spring and re-measure the length
• Repeat this with more mass until 6N is hanging from the spring
• Record results in a table

Question 30

What is the practical for Force and Acceleration?

Answer 30

Experiment 1: Varying force to see how it affects acceleration
* Make ramp for trolley to go down
* Have a pulley clamped to the desk so the trolley can go down the ramp
* Have a lightgate clamped to a stand to record the trolley’s speed
* Add a certain mass to the pulley and record initial speed, final speed and time taken
* From this you can find out the acceleration and the force on the pulley
* Repeat this with different masses on the pulley

Experiment 2: Varying mass to see how it affects acceleration
* Same as experiment 1, except add the mass to the trolley instead

Question 31

What are some car safety features?

Answer 31

Crumple Zones, Seatbelts, Airbags, Anti-lock Brakes, and Electronic Collision Avoidance Systems

Question 32

What is a crumple zone and how does it work?

Answer 32

It’s the area of a vehicle that is designed to crumple if the vehicle crashes, to absorb impact and dissipate the energy away from the driver and passengers

Question 33

What do seatbelts do?

Answer 33

Designed to keep people in their seats so they don’t get thrown around inside or outside the vehicle if it crashes

Question 34

What do airbags do?

Answer 34

Protects passengers from hitting the interior of the vehicle or objects outside of the vehicle. If the sensors detect a crash, then the airbags are filled with nitrogen in a fraction of a second

Question 35

What do anti-lock brakes do?

Answer 35

They prevent skidding by keeping the wheels from locking up during braking to maintain traction with the road surface

Question 36

What do electronic collision avoidance systems do?

Answer 36

Often found in newer cars, involves sensors to detect pedestrians and objects with accuracy. It alerts and assisters driver to avoid imminent crashes