2 is B. 3 is D. 4 is C. I think 5 is A. 6 is A. 7 is D. I think you are all correct. Good Luck!
<span>The correct answer is option B. i.e.invention of the microscope. Galileo Galilei invented the microscope and showed its use. Sir Issac Newton invented some part of the calculus, Also invented Newton's Laws of motion and the universal gravitation theory.</span>
Since power = work done/time, 60= work done/120, work done = 120*60 = 7200. So,work done = 7200N (Newton).
I'm not sure if you're supposed to convert the seconds to time.
The change in gravitational potential energy due to change in position must be the change in it's kinetic energy as the system is isolated! so find out the potential energies of the two different points!
<span>PE=−[G<span>M1</span><span>M2</span>]÷R
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Potential energy of a particle due to mass A is not affected by presence of any other mass B !</span>
