A child drags a 0.398 kg toy dog

across flat ground at constant speed,

with a 4.63 N force at a 63.0° angle.

What is the force of friction on the

toy?

(Hint: You do NOT need to know the

coefficient of friction.)

2.10 N

Explanation:

Draw a free body diagram of the toy. There are four forces:

Weight force mg pulling down,

Normal force N pushing up,

Friction force F pushing left,

Applied force 4.63 N pulling at an angle of 63.0°.

Sum of the forces in the x direction:

∑F = ma

4.63 N cos 63.0° - F = 0

F = 2.10 N