Friction and Circular Motion

Name: Friction and Circular Motion
Author: StemPy Lab

Friction stops a sliding box, and it also lets you walk and a car turn a corner. In this course we study static and kinetic friction, a block on a rough slope, and the force that keeps a body on a circle, which decides the safe speed of a car on a flat bend and on a banked road.

3 lessons, about 1 h 15 min3 simulations12 problems6 practice questionsPython in every lesson

Created by StemPy Lab

Course outline (3 lessons)

Lesson 1about 25 min
Friction: static and kinetic
Friction acts along a surface, against sliding or the tendency to slide. Static friction matches the push, up to a limit $f_{s,\max} = \mu_s N$ . Once the body slides, kinetic friction $f_k = \mu_k N$ is nearly steady, and a little less, since $\mu_k < \mu_s$ . Both depend on the two surfaces and on $N$ , not on the area of contact.
1 simulation2 practice questions1 Python program4 problems1 Python lab1 question set
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Lesson 2about 25 min
Motion on an inclined plane
On a slope, split the weight along the slope ( $mg\sin\theta$ ) and across it ( $mg\cos\theta$ ). The normal reaction is $N = mg\cos\theta$ . On a smooth slope $a = g\sin\theta$ . On a rough slope a block sliding down has $a = g(\sin\theta - \mu_k\cos\theta)$ . It starts to slide when $\tan\theta$ passes $\mu_s$ ; that angle is the angle of repose.
1 simulation2 practice questions1 Python program4 problems1 Python lab
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Lesson 3about 25 min
Force in circular motion: flat and banked roads
A body moving on a circle needs a net force toward the centre, $F = \dfrac{mv^2}{r}$ . It is not a new force: tension, friction, the normal reaction or gravity supplies it. On a flat bend friction does it, so $v_{\max} = \sqrt{\mu_s rg}$ . On a banked bend the tilted normal reaction helps, and with no friction at all $\tan\theta = \dfrac{v^2}{rg}$ .
1 simulation2 practice questions1 Python program4 problems1 Python lab1 note
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Test Your Learning

Friction, Slopes and Circular Motion: Practice Paper

20 questions · 40 min

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More onMechanics › Friction Mechanics › Newton's Laws of Motion Mechanics › Circular Motion

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Friction and Circular Motion

Course outline (3 lessons)

Friction: static and kinetic

Motion on an inclined plane

Force in circular motion: flat and banked roads

Test Your Learning

Your teacher

Discussion (0)