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WAEC Physics 2017 Paper

Question : 6

Total: 50

Solution:

Concept:

The net resultant force on the object gives its acceleration by Newton's second law:

F = ma

Explanation:

Weight of the object:

W = mg = 10 \times 10 = 100\,N

, acting vertically downward.

Resolve the

100\,N

force, which is inclined at

45^\circ

Horizontal component:

100\cos45^\circ = 70.7\,N

Vertical component:

100\sin45^\circ = 70.7\,N

Net horizontal force:

F_x = 70.7 + 60 = 130.7\,N

Net vertical force downward:

F_y = 100 - 70.7 = 29.3\,N

Resultant force:

F = \sqrt{F_x^2 + F_y^2}

F = \sqrt{130.7^2 + 29.3^2} \approx 133.9\,N

Using

F = ma

a = \frac{F}{m} = \frac{133.9}{10} = 13.4\,ms^{-2}

Answer:

13.4\,ms^{-2}

(Option B).

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