Aflexible shaft consists of a 3 mm diameter steel wire in a flexible hollow tube which imposes a frictional torque of 0.04 n m per meter when the shaft rotates. the shaft is to be used for applying a torque of 0.1 n m to actuate a switch. what is the maximum length of shaft that may be used if the shear stress in the shaft is not to exceed 50 mpa?

2.5m

Explanation:

Torque is defined as the rotational effect of a force on a body.

The torque T for the maximum shear stress is given as 0.1 Nm

Frictional torque is the torque caused by a frictional force

The frictional torque F is given as 0.04 Nm/m

The maximum length of the shaft is thus given as

L = T / F

  = 0.1/0.04

L= 2.5 m

i think the answer would be reserve.

air exerts forces on falling objects near earth’s surface.

explanation:

the term 'free falls' refer to object that are falling towards the earth, in a situation in which gravity is the only force acting on the object.

for an object in free fall, the acceleration is constant (g, the gravitational acceleration), and so the velocity of the object constantly increases.

for objects near earth's surface, there is always another force acting on the object: the resistance due to the air. this force is opposed to the direction of fall of the object, and it is proportional to the velocity of the object, so as the object falls down, this force increases up to a point when it balances the force of gravity, and the object continues its motion at constant velocity (called terminal velocity). since in this case gravity is not the only force acting on the object, we are not in a situation of free fall.