Year 10 Advanced Science – Motion and Forces

Homework 2Name: ______

  1. Define the Newton’s 3 laws each with an example.[ 6 marks ]

Laws / What is it? / An Example
1st
2nd
3rx
  1. Two cars accelerate away from traffic lights. How could you tell which had the greatest acceleration? [1]
  2. An object has zero acceleration. What does it mean? [1]

A The object is at rest.

B The object is travelling at a constant speed.

C The object is travelling at a constant velocity.

D All of the above.

  1. Explain why deceleration is always a negative number. (refer to the formula of acceleration) [2]
  2. Explain how acceleration can be calculated from a velocity–time graph. (Use an annotated diagram to represent your answer). [3]
  3. Which of these graphs represents:(explain your answer) [4]

a slow acceleration

b quick acceleration

c no acceleration

d deceleration?

  1. Calculate the area and the gradient of each section of this v–t graph. What does this area represent? [3]
  2. How much speed is gained every second if acceleration is 15 m/s2?
  3. A car accelerates from rest to 50 km/h in 5 s. What is the acceleration of the car in:

a km/h/s

b m/s2?Speed

  1. a) In 2001, the Victorian suburban speed limit was dropped from 60 km/h to 50 km/h. What difference did it make to stopping distances?

b)It is recommended that the distance between your car and the car in front be equivalent to the reaction distance at that speed. How many car lengths should a driver travelling at 60 km/h and 100 km/h leave in front of them?

  1. Give an explanation for the following: [4]

a) Explain why an unbelted occupant of a car will probably hit their head on the windscreen in a head-on car collision.

b) What features are designed to comfortably stop our forwards inertia in a car?

c)What are the advantages of the stopping force being applied to the chest instead of the head?

d) Explain why modern cars are fitted with headrests.

  1. Explain what happens to the occupants when the car they are in:

a turns left

b suddenly accelerates

c goes fast over a speed hump

d goes over a deep dip in the road

e collides head-on into a wall

f is parked, but is hit from behind by another car

g is parked, but is hit from the left by another car.

  1. a) What is the net force in the this situation?
    b) Explain these forces.
    c) Find the acceleration.
  2. What force is being applied if a:

a 5 kg box accelerates at 4.1 m/s2

b 1.3 tonne car accelerates at 2 m/s2

c 400 g ball accelerates at 4 m/s2?

15 What is the acceleration caused by a:

a 40 N force applied to a 0.5 kg mass

b 0.5 N force applied to a 50 kg mass?

16 A 35 N force caused a mass to accelerate at 7 m/s2. What was the mass?

17 A 3.5 kg body accelerates from rest to 20 m/s in 5 s. Calculate:

a its acceleration

b the force required.

18 The brakes of a car can exert a stopping force of 3000 N. The car is 1.5 t.

a What is the mass of the car in kg?

b Calculate the deceleration of the car.

c Would this be positive or negative acceleration?

d How long would it take to stop travelling initially at 10 m/s?

19 a Explain why the acceleration of a rocket increases as its fuel is consumed.

b Rockets normally discard used fuel tanks soon after launch. What is the advantage of this?

  1. Explain why a balloon shoots around the room when it is allowed to deflate.

21. Firefighters often need to brace themselves or have extra help to hold a firehose while it is on. Explain why. What would happen if they did not have this help?nearby hard ground.

  1. Craig throws a netball.

a What is the action force?

b What did it do?
c What was the reaction force and what did it do?

  1. Ben kicks a football. Draw the action–reaction pair of forces acting on the football:

a as it lies on the ground waiting to be kicked

b as it is kicked, Ben’s boot touching the ball

c as it flies through the air, having no more contact with the foot.

24. Give 4 differences between Mass and Gravity

Mass / Gravity

25. Lisa has a mass of 55 kg. What would be her mass and her weight on:

a Earth (g = 9.8 m/s2)

b the Moon (g = 1.63 m/s2)

c Mars (g = 3.7 m/s2)?

26. Dylan lands on the Planet Cochon. His mass is 70 kg on Earth.

aWhat would be his mass on Cochon?

b If his weight on Cochon is 350 N, what is the acceleration due to gravity on Cochon?

c Is Cochon bigger or smaller than Earth?