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.
Ice is a solid state and water vapor is gas. Gas comes from water being heated. Plasma is also a fourth, less known, state of matter. I hope this helps. :)
The graph is one single line and, as a system solution refers to an intersection point (in other words, a point in common), we affirm both equations share all of their points and thus, such system has infinite solutions.
