Q21 · 2020 · Paper 1Simple familiar3 marks
QUESTION 21 (3 marks)
An object that is 7.12 × 10^6 m from the centre of the Earth experiences a gravitational force of 2.84 kN. Calculate the mass of the object.
WORKED SOLUTION
3 marksQCAA guide · typeset solution
ANSWER
See worked solution below.
Worked solution
𝐹𝐹= 𝐺𝐺𝐺𝐺𝐺𝐺
𝑟𝑟2
𝑚𝑚= 𝐹𝐹𝑟𝑟2
𝐺𝐺𝐺𝐺
𝑚𝑚= 2.84 × 103 × (7.12 × 106)2
6.67 × 10−11 × 5.97 × 1024
Mass = 362 kg
• indicates an understanding of the physical scenario
in relation to Newton’s law of universal gravitation or
other relevant physical concept/s [1 mark]
• provides pertinent mathematical operation/s correctly
performed [1 mark]
• determines the mass [1 mark]
One QCAA sample method typeset for web; criterion wording is adapted from the official marking guide.
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