Q on Static Friction - (from Giancoli)

[milky9311]

Hello

I do not understand the answer given, i may be thinking too hard?


Q: "What is the maximum acceleration a car can undergo if the coefficient of static friction between the tires and the road is 0.90?"

A:"The static frictional force is the accelerating force, and so F(friction) = ma. If we assume the maximum acceleration, then we need the maximum force, and so the static frictional force would be its maximum value of mu(static) F(normal)"

How can the static friction be the max acceleration? A car's max acceleration from rest cannot be fixed as it depends on the power engine and not the road?
Can't a car exert more acceleration than the static friction force.

Thanks in advance

 

[ehild]

It sounds strange but the car is not really accelerated by the engine. The engine exerts a torque on the tyres; the tyres exert force on the ground, the ground pushes back and that force from the ground drives the car forward. The interaction between the tyres and the ground is the static friction.

ehild

 

[PhanthomJay]

How can the static friction be the max acceleration? A car's max acceleration from rest cannot be fixed as it depends on the power engine and not the road?
Can't a car exert more acceleration than the static friction force.

Thanks in advance

No. Just imagine a car on an icy frictionless surface. You can rev up the engine to its maximum power output, and the car will not accelerate at all, the wheels will just spin in place.

 

[milky9311]

aaaahhhh

thanks to both of you

I understand now

Thanks again