A 55 kg pole-vaulter reaches a speed of 11 m/s just before planting the pole for the vault. a. If he has a speed of 0.5 m/s when he crosses the bar, what height can he clear?
b. If the mats he lands on are piled 1.5 m high, at what speed does he hit the mats?

PEG = 0.8*KE.
M*g*h = 0.8 *(0.5*M*v^2) M, h, and v are the vaulter's mass, height, and speed, respectively.
g*h = 0.8*0.5*v^2 Divide both sides by M (the mass).
g*h = 0.4*v^2

(9.81 m/s^2)*h = 0.4*(7 m/s)^2. Note that m and s denote meter and second, respectively.
h = 0.4*(7 m/s)^2 /(9.81 m/s^2) Divide both sides by 9.81 m/s^2. Also, note that m is NOT mass here.
= 0.4*(49 m^2/s^2)/(9.81 m/s^2)
= 0.4*49 m/9.81

Answer = 1.99796 meters

Magma  is composed of molten rock and is  stored  in the earth's crust. lava is  magma  that reaches the surface of our planet through a volcano vent.