Q24 · 2021 · Paper 1Simple familiar3 marks
QUESTION 24 (3 marks)
The diagram shows a 1.5 kg object on an inclined plane with an angle of up from the horizontal. The object experiences a frictional force of 4.5 N.
Calculate the magnitude of the net force acting on the object.
WORKED SOLUTION
3 marksQCAA guide · typeset solution
ANSWER
See worked solution below.
Worked solution
𝐹𝑔,𝑥= 𝑚𝑔𝑠𝑖𝑛 𝜃= 1.5 × 9.8 × sin 30 = 7.4 N
𝐹𝑛𝑒𝑡= 𝐹𝑔,𝑥−𝐹𝑓= 7.4 −4.5 = 2.9 N
Magnitude of net force = 2.9 N (to 1 decimal place)
• identifies the forces acting on the object [1 mark]
• calculates the component of the gravitational
force acting down the slope [1 mark]
• calculates the magnitude of the net force
[1 mark]
One QCAA sample method typeset for web; criterion wording is adapted from the official marking guide.
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