Question

A small car might have a mass of around 1000 kg and a coefficient of static friction of about 0.9.

- What is the largest possible force that static friction can exert on this car? (in N)

- What is the smallest possible force that static friction can exert on this car?

- Describe situations when each of the above cases would occur.

Answer 1

When an object is at rest, static friction is zero. When we applied a small force on that object, static friction is establishes an equal and opposite force that keep the object at rest.

As we increase the applied force, static frictional force also increase to match the force and keep that object is at rest. There is a maximum static friction force. When this maximum static force is exceeded, the object start moving. If F is the applied force then condition for object to be at rest,

  

And

So the maximum static force is given by,

Where,

: coefficient of static friction.

N: Normal force.

As normal force acts upward due to ground and it balance the force due to gravity (mg, where m is mass of object and g is gravitational acceleration and g=9.8 m/s² ).

Given:

mass of car m=1000 Kg

Coefficient of static friction =0.9

So, Maximum static frictional force,

So maximum static fictional force is 8.82 KN.

Minimum static force is zero.

Please upvote if it helps and If you have any doubt, feel free to discuss in the comments.