1. How much heat energy is required to raise the temperature of a 5 kg aluminium bar from 28°C to 68°C ?
( Specific heat capacity of aluminium = 900 J kg C)

180 kJ

Explanation:

Given that:

Mass (m) = 5 kg

Initial temperature (T1) = 28°C

Final temperature (T2) = 68°C

The change in temperature (ΔT) = T2 - T1 = 68°C - 28°C = 40°C

Specific heat capacity of aluminium (c) = 900 J/kg°C

The quantity of heat energy required (q) is given by:

q = mcΔT

q = 5 kg × 900 J/kg°C × 40°C

q =  180000 Joules

q = 180 kJ

Therefore 180 kJ is required to raise the temperature of aluminium from 28°C to 68°C.

b. false

explanation:

suppose a rock in free fall is dropped off a cliff. after falling for 5 seconds, its speed would not be 100 m/s.