The Kepler's laws predict the planetary motion, so there are three laws for this, namely:
1. The orbit of a planet is an ellipse with the Sun (the sun is a star!) at one of the two focus.
2. A line segment joining a planet and the Sun sweeps out equal areas during equal intervals of time.
3. The square of the orbital period of a planet is proportional to the cube of the semi-major axis of its orbit.
So, let's use second law. The Sun sweeps out equal areas during equal intervals of time means that if A = B, the time the planet takes to travel A1A2 is equal to the time the planet takes to travel B1B2, but given that A = 2B, then takes twice the time to travel A1A2 compared to B1B2.
watts = work per second.
work is mgh = 3x10x50=1500
watts out = 1500
Watts used = 2000
eff=1500/2000=75%
Explanation:
s = ut + 1/2 a t^2
200 = 0 * 6 + 1/2 * a * (6)^2
200 = 1/2 * a * 36
200 = 18 a
a = 200/18
a= 11.1m/sec^2
v = u + at
v = 0 + 11.1 * 6
v = 66.6m/s
hope it helps you
