A 5.0 kg block slides down a 30° incline at constant velocity. Taking g = 9.8 m/s², calculate the friction force acting on the block.

Dynamics Challenge #4 — Inclined Planes

Friction on
an incline.

Dynamics Medium

Problem

A 5.0 kg block slides down a 30° incline at constant velocity. Calculate the friction force acting on the block.

Mass\( m = 5.0\ \mathrm{kg} \)
Incline angle\( 30^{\circ} \)
Motionconstant velocity
Gravity\( g = 9.8\ \mathrm{m/s^2} \)

Constant velocity is the key phrase — it fixes the net force before any trigonometry.

Hint: constant velocity means zero net force along the slope — friction must exactly balance the pull of gravity along the incline, \( mg\sin\theta \).

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Friction onan incline.

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Friction on
an incline.