A metal block is made from a mixture of 2.4 kg of aluminium, 1.6 kg of brass and 0.8 kg of copper. The amount of heat required to raise the temperature of this block from 20° C to 80° C is (specific heats of aluminium, brass and copper are 0.216,0.0917 and 0.0931 cal kg -1 ° C -1, respectively)

Question

A metal block is made from a mixture of 2.4 kg of aluminium, 1.6 kg of brass and 0.8 kg of copper. The amount of heat required to raise the temperature of this block from 20° C to 80° C is (specific heats of aluminium, brass and copper are 0.216,0.0917 and 0.0931 cal kg -1 ° C -1, respectively) (A) 96.2 cal (B) 44.4 cal (C) 86.2 cal (D) 62.8 cal

Tardigrade Admin · Accepted Answer

Given, m1=2.4 kg , m2=1.6 kg , m3=0.8 kg s1=0.216 cal kg -1 ° C -1, s2=0.0917 cal kg -1 ° C -1, s3=0.0931 cal kg -1 ° C -1 and Δ T=T2-T1=(80-20)° C =60° C Q =m1 s1 Δ θ+m2 s2 Δ θ+m3 s3 Δ T =(2.4 × 0.216+1.6 × 0.0917+0.8 × 0.0931)(60) =44.376 cal ≈ 44.4 cal

96.2 cal

44.4 cal

86.2 cal

62.8 cal

Given, m1​=2.4kg,m2​=1.6kg,m3​=0.8kg s1​=0.216calkg−1∘C−1, s2​=0.0917calkg−1∘C−1, s3​=0.0931calkg−1∘C−1 and ΔT=T2​−T1​=(80−20)∘C=60∘C Q=m1​s1​Δθ+m2​s2​Δθ+m3​s3​ΔT =(2.4×0.216+1.6×0.0917+0.8×0.0931)(60) =44.376cal≈44.4cal