Answer:
Tension is also known as Force...
and Force is mass× acceleration.
so....1000×0.70=700N
I like to think of it this way:
... Gravity pulls on heavy objects with more force than light objects.
(That's why they're "heavy".)
... Heavy objects are the ones with more mass. Light objects are the ones with less mass.
... Gravity is pulling on more mass with more force, and on less mass with less force.
... But from Newton's 2nd law of motion, we know that it takes more force to accelerate more mass, and less force to accelerate less mass.
That's exactly what gravity is doing. So the heavy object with more mass, and the light object with less mass, wind up with the same acceleration.
There you go. With zero math !
Classical physics considered light to behave as a wave in all environments; it had a set amplitude, frequency etc. The problem was that this meant that there was a continuous variation in its properties, hence if the amplitude of the light was incresed by a bit, a phenomenon like the phhotoelectric one would become only marginally more apparent. However, in this case, there is a cutoff point which means that the only-wave theory had to be wrong.
