Heat a. Calculate the time required for an
electric water heater to raise
temperature of 10 litres of water
from 15°C to 65°C, if the heating
element takes a current of 10A from
a 240V supply and the efficiency of
the heating process is 80%. Take
specific heat capacity of water to be
4180J/Kg and 1kg of water as 1 litre.​

If a rock is thrown upward on the planet mars with a velocity of 12 m/s, its height (in meters) after t seconds is given by h = 12t − 1.86t2. (a) find the velocity of the rock after two seconds. m/s (b) find the velocity of the rock when t = a. 12−3.72a m/s (c) when will the rock hit the surface? (round your answer to one decimal place.) t = s (d) with what velocity will the rock hit the surface? m/s