A97-kg sprinter wishes to accelerate from rest to a speed of 11 m/s in a distance

coefficient of static friction required between the sprinter's shoes and the track is  u=0.293.

Explanation:-  

The frictional coefficient is found from newton’s second law

We know that  

Compare the Eqn (1) and eqn (2)  

Mass (m) cancel each other both side

So

Coefficient of static friction    

We know that  

Kinetics    

Substitute the value of acceleration in eqn (3)

So that

Coefficient of static friction.

Coefficient of static friction    

Q₂ = 5833.33 J

Explanation:

First we need to find the energy supplied to the heat engine. The formula for the efficiency of the heat engine is given as:

η = W/Q₁

where,

η = efficiency of engine = 30% = 0.3

W = Work done by engine = 2500 J

Q₁ = Heat supplied to the engine = ?

Therefore,

0.3 = 2500 J/Q₁

Q₁ = 2500 J/0.3

Q₁ = 8333.33 J

Now, we find the heat discharged to lower temperature reservoir by using the formula of work:

W = Q₁ - Q₂

Q₂ = Q₁ - W

where,

Q₂ = Heat discharged to the lower temperature reservoir = ?

Therefore,

Q₂ = 8333.33 J - 2500 J

Q₂ = 5833.33 J