Direction of Frictional Force on Tyre or Wheel

For these type of questions, it is important to identify which tyre/wheel is connected/powered by the engine or the person.

On each tyre or wheel, there are actually two types of frictional force.

1. Frictional force on wheel

2. Frictional force on road/ground

You can view the explanation plus the 4 examples from Olevel p1 in the video below.

https://youtu.be/NHI7C1WBUJg

Examples used in the video.

2007PP P1Q5 Answer: Option D

2004PP P1Q5Answer: Option D

2020PPp1q6 Answer: Option B

2021PP P1Q7 Answer: Option C

Understanding Newton’s 1st and 2nd Laws of Motion

1) Newton’s first law states that an object will remain at rest or in uniform motion (constant speed) in a straight line unless an external force acts on the body.

In other words, when a body is at rest or moving at constant speed in a straight line (constant velocity), straight away you should know it is Newton’s first law. Next you must know these 3 basics concepts about 1st law:

– forces acting on the body are balanced

– net force / resultant force acting on the body is zero

– there is no acceleration.

2) Newton’s second law states that when a net force (resultant force) acts on a body, it will cause an acceleration on the body (accelerating or decelerating).

Basically F = ma where F is the net or resultant force in N,m is the mass in kga is the acceleration in ms-2

In other words, when a body is moving faster or slower (or going round a bend), you should know its Newton’s second law. Next you must know these 3 basic concepts about 2nd law:

– forces acting on the body are not balanced

– there is a net force / resultant force acting on the body

– there is an acceleration (accelerating of net force is in the direction of motion, or decelerating if the net force is opposite to the direction of motion)

https://youtu.be/VOJDqbrEs_0

Newton's Law