Page 18 - Q & A STPM 2022 Physics

Physics Semester 1 STPM Chapter 1 Physical Quantities and Units
Question 5

The diagram shows two tugs pulling a boat in a river along the direction due
North.

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15°
300 N 180 N
30° Semester

1

(a) Find the total vertical force acting on the boat.
(b) Find additional force needed to apply to the boat so that the boat continues
to move in a direction due North.

Answer:
(a)

180 cos 30°
300 cos 15°
15°
300 N
30° 180 N

300 sin 15° 180 sin 30°

Total vertical force = 180 cos 30° + 300 cos 15°
= 445.7 N
(b) Total horizontal force
= 180 sin 30° + (–300 sin 15°)
= 12.35 N
∴ Additional force of 12.35 N applied due West is needed.

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01 STPM Q&A PHY T1.indd 9 17/02/2022 10:03 AM