Question in attachment !!
Answers
1. work done = force*displacement
kinetic energy = 1/2mv^2
change in kinetic energy = 1/2mv^2 - 1/2mu^2
force = mass*acceleration (newtons II law)
work = m*a*s
a*s = v^2-u^2 /2 (third law of motion)
= m(v^2-u^2 /2)
After multiplying:
=1/2mv^2 - 1/2mu^2 which is change in kinetic energy
Answer: Hence proved
2. To prove: weight on moon = 1/6 weight on earth
Weight = Mass*Gravitational acceleration
dividing Weight on earth by weight on moon for ration
=W(earth) / W(moon)
= M*g (earth) / M*g(moon)
=g(earth) / g(moon)
now g = GM/d^2 (from universal law of gravitation)
= 6*10^-11 * 6*10^24/(6*10^6)^2----> radius of earth is distance and mass of earth is M
=36*10^13 / 36*10^12
=10
=6*10^-11 * 7*10^22/(1*10^6)^2----->radius of moon is d and mass of moon is M
=1.6
=10/1.6
=6/1
so weight on earth is 1/6 the weight on moon.
3.
work done = Force* d
force = mass* acc.
taken acc. as g and d as height
force = mgh = potential energy
4. 1kwh(commercial unit) = 3.6*10^6 Joule