Explanation:
(i) Height of tree, h = 4 m
Mass of Ninja, m = 30 kg
The gravitational potential energy on the top branch of the tree is given by :

g is acceleration due to gravity

(ii) If he were at a height of 2 meters from the ground, its potential energy will be :

g is acceleration due to gravity

Therefore, this is the required explanation.
Answer: See explanation
Explanation:
The density would like be calculated by dividing the mass by volume. This will be:
Density = Mass / Volume
Density = 390 / 50
Density = 7.8g/cm
Power used by the clock=1.03 W
Explanation:
resistance= 14000 ohm
voltage=120 V
The formula for the power is given by

P=(120)²/14000
P=1.03 W
The gravitation acceleration on the moon is different than on Earth. It is 1.6 m/s^2. If you weigh 120 lbs, then you would multiply 120 pounds by the gravitational acceleration on the moon and then divide by the acceleration on Earth.
(120 lbs * 1.6) / 9.8 = 20 pounds.
The mass will always be the same no matter what planet you’re on, so it’s still 54 kg.