Daniddmelo says it right there, don't know why he got reported.
The potential energy (PE) is mass x height x gravity. So it would be 25 kg x 4 m x 9.8 = 980 joules. The child starts out with 980 joules of potential energy. The kinetic energy (KE) is (1/2) x mass x velocity squared. KE = (1/2) x 25 kg x 5 m/s2 = 312.5 joules. So he ends with 312.5 joules of kinetic energy. The Energy lost to friction = PE - KE. 980- 312.5 = 667.5 joules of energy lost to friction.
Please don't just copy and paste, and thank you Dan cause you practically did it I just... elaborated more? I dunno.
Explanation:
For a circular orbit v= 
with G = 6.6742 × 
Given m = 6.42 x 10^23 kg and r=9.38 x 10^6 m
=> v = 2137.3 m/s
I hope this is the correct way to solve
A proton has positive charge of 1, that is, equal but opposite to the charge of an electron. A neutron, like the name implies, is neutral with no net charge. The charge is believed to be from the charge of the quarks that make up the nucleons (protons and neutrons).
Physics is branch of science which deals with the properties of matter and their energies. And coming to science it is a systemic enterprise that builds and organizes knowledge in t eatable explanations and predictions about the universe.
