Assume that the kinetic energy of a 1500 kg car moving at 110. km/h could be converted entirely into heat.

What amount of water could be heated from 20°C to 55°C by the car's energy?

help! (:
explain the answer please and thank you!

ok - so original ke = 0.5mv^2. remember for this to be in joules m and v must be in metres per second and kg. so 110 km/h = 110/3.6 = 30.6 ms^-1 . substituting into the equation we get ek = 700200J. Thermal energy = m x c x change in temperature .m = mass of water in grams, c = 4.2 (specific heat capacity). therefore mass = heat energy divided by (temp change x 4.2) = 700200/(35 x 4.2) = 4700g = 4.7kg.
hope this helps

You are in Tanizaki's class. Shame on you. :P

Report Abuse

Assume that the kinetic energy of a 1500 kg car moving at 110. km/h could be converted entirely into heat.?
What amount of water could be heated from 20°C to 55°C by the car's energy?

KE = ½ * mass * velocity^2
velocity in m/s = 110 km/hr * 1000 m/km ÷ 3600 sec/hr = 30.556 m/s
KE = ½ * 1500 * (30.556)^2

Heat energy = mass * * Specific heat * ∆Temperature = mass * 4186 * 35

mass * 4186 * 35 = ½ * 1500 * (30.556)^2