A particular steel beam is able to survive 25,000 cycles of a cyclic stress of 150 MPa (alternating from tension to compression) and is able to survive 10,000 cycles of a cyclic stress of 200 MPa (alternating from tension to compression). If that beam is subjected to 15,000 cycles of stress of 150 MPa (alternating from tension to compression), how many additional cycles of stress of 200 MPa (alternating from tension to compression) can it withstand before breaking

the body's situation won't change the forces are equal opposit and on the same body

a and c

c is 100% but i am confused in a

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.