Topic Menu

Cyber-chess a chess instruction site

GCSE Questions: Forces

Q23. Buffy investigated the acceleration of a trolley. The diagram shows how she set up the apparatus.

(a) Before attaching the mass holder Buffy placed the trolley at the top of the runway.

The trolley rolled down the runway without being pushed.

Which of the following changes to the apparatus could be made to prevent the trolley from starting to roll down the runway? Tick one box.

Move the wooden block to the left.
Shorten the length of the runway.  
Use a taller wooden block  

I found this question confusing! The obvious thing to do would be to put a block on the slope to stop it moving - one you can remove when you want it to roll! 'Moving it to the left' would make the slope less steep - and I suppose it might stop it rolling - but only by moving it far left (from under the slope altogether) would definately stop it moving!

In my opinion this is a poor question - but there you go!

The other two choices were obviously wrong so it was the only one left....

[1 mark]

(b) Buffy attached the mass holder to the string. The string rubbed along the edge of the bench as the mass holder fell to the floor. Suggest what she could do to prevent the string from rubbing.

She could use a pulley wheel on the edge of the bench.

[1 mark]

(c) The light gate and data logger were used to determine the acceleration of the trolley.

Buffy increased the resultant force on the trolley and recorded the acceleration of the trolley in the table below.

Resultant force/N
Acceleration/ ms-2
0.05
0.08
0.10
0.18
0.15
0.25
0.20
0.32
0.25
0.41

 

Here is an incomplete graph of the results:

Complete the graph for Buffy.

Choose a suitable scale for the x-axis. Maximise use of the paper

Plot the results. Neat crosses at correct points

Draw a line of best fit. Use a ruler and sharp pencil!

[4 marks]

(d) Describe the relationship between the resultant force on the trolley and the acceleration of the trolley.

The resultant force on the trolley and the acceleration of the trolley are directly proportional to each other.

Just saying there is a positive correlation got you no mark.

[1 mark]

(e) Describe how the investigation could be improved to reduce the effect of random errors.

You need to repeat the measurements/investigation and then ignoring anomalies, calculate the mean / average values.

[2 marks]

(f) Write down the equation that links acceleration (a), mass (m) and resultant force (F).

F = ma

[1 mark]

(g) The resultant force on the trolley was 0.375 N.

The mass of the trolley was 0.60 kg.

Calculate the acceleration of the trolley.

Give your answer to 2 significant figures.

F = ma

0.375 = 0.60 x a

a = 0.375/0.60

a = 0.625 m/s2

a = 0.63 m/s2 (2 sf)

[4 marks]

[14 Marks TOTAL]