Lesson: Chapter 5 — Friction

Solving friction problems 7 of 7 Reset answers

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Question 7

An object of mass 2 kg is sliding along a table. It is pulled with a horizontal force of 9 N and the dynamic friction acting on it is 3 N. What is its acceleration?

A 4.5 m s⁻² B 6 m s⁻² C 1.5 m s⁻² D 3 m s⁻²

The right answer is the one marked above.

3 m s⁻².

F = 9 − 3 = 6 N

a = F ÷ m = 6 ÷ 2 = 3 m s⁻²

4.5 m s⁻² is 9 ÷ 2 — the friction forgotten. Here the mass is given directly in kilograms, so there is no dividing by g to do: read the units in the question before you start.

Answer the question to continue.