Question

A 63 kg boy and sled are pulled along level ground with a force of 577 N. The boy and sled
are moving at a constant velocity of 2.4 m/s. What is the size of the frictional force?

Answer 1

Answer:

The size of the frictional force is 577 N.

Explanation:

What is frictional force?

Frictional forces are exerted every time you have two surfaces sliding across one another. Friction depends on:

• how rougher are the surfaces on contact;
• how harder you push one surface to the other.

There are two types of friction:

• static friction $f_s$;
• dynamic (sliding) friction $f_d$.

Now let's attack the problem:

First, you have to write the data down:

$\bullet \quad m= 63\,kg\\\\\bullet \quad F= 577\,N\\\\\bullet \quad v= 2.4\,m/s$

If the boy and the sled moves on constant velocity, Newton's First Law Of Motion states that the net force acting on them must be zero:

$F_{net}=0$

Applying Newton's Second Law Of Motion, we get:

$F-f_d=0$

which means that:

$F=f_d$

In other words, the dynamic frictional force equals the force that moves the boy and sled. So we may write:

$\boxed{f_d=577\,N}$

Conclusion: the size of the (dynamic) frictional force is 577 N.

Happy studying!

Brainly Team