Govt. Exams
Entrance Exams
In isothermal process, temperature is constant. For ideal gas, internal energy U depends only on temperature, so U remains constant.
According to the second law of thermodynamics, entropy of an isolated system always increases or remains constant, never decreases.
By first law: ΔU = Q - W = 500 - 200 = 300 J (where W is work done by system)
Newton's third law states that for every action, there is an equal and opposite reaction force.
f = μN = μmg = 0.25 × 8 × 10 = 20 N
At maximum height, v = 0. Using v = u - gt: 0 = 20 - 10t, so t = 2 s
Using s = ut + ½at², where u = 0, s = 100 m, t = 5 s: 100 = 0 + ½a(25), a = 8 m/s²
Maximum resultant occurs when forces act in the same direction: R = 12 + 5 = 17 N
Using F = ma, where a = (v-u)/t = (0-10)/2 = -5 m/s². Therefore F = 5 × 5 = 25 N
At maximum height, v = 0. Using v = u - gt, 0 = 20 - 10t, therefore t = 2 s
