Forces and motionIB MYP Sciences: Topic test

20 questions, 54 marks

IB MYP Sciences

Forces and motion topic test

Total 54 marks

Name

Class

Date

1
A runner on a 400 m oval track in Kingston completes one lap in 80 s at a steady speed.
(a)
What is the runner's average speed?
[1 mark]
A0.2 m/s
B320 m/s
C5 m/s
D32 000 m/s
(b)
Which of these quantities is a vector?
[1 mark]
ASpeed
BDistance
CTime
DVelocity
(c)
Explain why the runner's velocity is not constant even though her speed is constant.
[2 marks]
Total for question 1: 4 marks
2
A shopper in Manila lifts a 3.0 kg bag of rice from a shelf. On Earth the gravitational field strength is 10 N/kg.
(a)
What is the weight of the bag of rice on Earth?
[1 mark]
A30 N
B0.30 N
C13 N
D300 N
(b)
The shopper slides the bag across the shelf. Which force acts on the bag in the direction opposite to its motion?
[1 mark]
AWeight
BFriction
CThe upward contact force from the shelf
DThrust from a motor
(c)
The bag is taken to Mars, where the gravitational field strength is 3.7 N/kg. State the mass of the bag on Mars and calculate its weight there.
[2 marks]
Total for question 2: 4 marks
3
A delivery cyclist in Hanoi and her loaded bicycle have a total mass of 90 kg. When she starts from rest, her pedalling gives a driving force of 150 N and the resistive forces total 60 N.
(a)
Calculate the resultant force on the cyclist and her acceleration.
[3 marks]
(b)
She keeps accelerating at this rate for 5.0 s. Calculate her speed after 5.0 s. She then travels at a constant speed with the driving force still 150 N. State the size of the resistive force at this constant speed and explain why her speed is constant.
[4 marks]
Total for question 3: 7 marks
4
A sports-shoe company in Portland wants to know which sole material gives the most grip. Three materials are being considered: rubber, foam and leather. Grip depends on the friction force between the sole and the floor.
(a)
Plan an investigation, using a newtonmeter, to test a hypothesis about how the sole material affects the friction force on a dry floor. In your answer, state your hypothesis with a scientific reason, identify the variables, and describe a safe method.
[6 marks]
(b)
In a trial, a technician dragged a different shoe, with a different mass, once across a dry wooden floor for each sole material. The pulling forces recorded were 8.1 N for rubber, 4.9 N for foam and 3.2 N for leather. The technician concluded that rubber gives the best grip on every surface. Evaluate the method and the conclusion.
[6 marks]
Total for question 4: 12 marks
5
An express lift in a tall building in Seoul starts from rest, speeds up steadily to 6.0 m/s in 3.0 s, then moves at a steady 6.0 m/s for 20 s, and finally slows steadily to rest in 3.0 s.
(a)
What is the acceleration of the lift during the first 3.0 s?
[1 mark]
A0.5 m/s²
B3.0 m/s²
C18 m/s²
D2.0 m/s²
(b)
What is the total distance travelled by the lift?
[1 mark]
A120 m
B138 m
C26 m
D156 m
(c)
A velocity–time graph is drawn for the journey. Describe the gradient of the graph during the 20 s of steady motion and state what this shows about the lift's acceleration.
[2 marks]
Total for question 5: 4 marks
6
Engineers are building a reservoir dam in the Andes in Peru. The water in the reservoir is very deep and it pushes on the wall of the dam.
(a)
How does the water pressure on the dam wall change with depth?
[1 mark]
AIt increases, because there is more water above
BIt decreases, because the water is cooler
CIt stays the same, because water is a liquid
DIt changes only with the width of the reservoir
(b)
The water exerts a force of 3 000 000 N on a section of the wall with an area of 50 m². What is the pressure on this section?
[1 mark]
A150 000 000 Pa
B2 999 950 Pa
C60 000 Pa
D0.000 017 Pa
(c)
Explain why the wall of the dam is built much thicker at the bottom than at the top.
[2 marks]
Total for question 6: 4 marks
7
A gardener in Pune uses a wheelbarrow to move wet soil. The load weighs 600 N and acts 0.40 m horizontally from the axle of the wheel, which is the pivot. She lifts the handles at a distance of 1.2 m from the axle. Ignore the weight of the wheelbarrow itself.
(a)
Calculate the moment of the load about the axle and the smallest upward force she must apply to the handles to lift the load.
[3 marks]
(b)
She then pushes the loaded wheelbarrow 25 m along level ground with a force of 80 N. Calculate the work done. Explain why longer handles would let her lift the load with a smaller force.
[4 marks]
Total for question 7: 7 marks
8
A space agency launches a rocket carrying a weather satellite. At lift-off, hot gases are pushed out of the rocket's engines downwards at very high speed. Later, far from any planet, the engines are switched off.
(a)
Explain the motion of the rocket at lift-off and after the engines are switched off, using Newton's three laws of motion.
[6 marks]
(b)
Evaluate the decision of a government to spend a large part of its science budget on launching weather satellites. Consider the social, economic and environmental impacts, and reach a justified conclusion.
[6 marks]
Total for question 8: 12 marks

End of questions

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).