This section includes many important NEET Physics problems in Joule’s Law topic of Thermodynamics concepts that are considered to be very important from NEET exam point of view.
Designed for NEET aspirants, this resource helps in mastering key problems in Joule’s Law, Thermodynamics. Each question is solved with a detailed step by step explanation to build strong conceptual clarity.
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NEET Physics Problems in Joule’s Law topic in Thermodynamics Concepts and their Solutions with Detailed Step by Step Explanation.
Thermodynamics – Joule’s Law
🟩 Problem 1:
A man of 60 kg gains 1000 cal of heat by eating 5 mangoes. His efficiency is 56%. To what height he can jump by using this energy?
Options:
(1) 4 m (2) 20 m (3) 28 m (4) 0.2 m
✅ Solution:
Step 1: Convert Heat Energy from Calories to Joules
The man gains 1000 calories of energy by eating 5 mangoes. Since 1 calorie = 4.184 joules, we convert total energy into joules: Total energy = \( 1000 \times 4.184 = 4184 \text{J} \)
Step 2: Calculate usable energy from the person’s efficiency
Given, His efficiency is only 56%, so only 56% of that is converted into usable mechanical energy:
Usable Energy = \( \frac{56}{100} \times 4184 = 2343.04 \) J
Step 3: Use Energy to Calculate Maximum Height
The usable energy will be entirely converted to gravitational potential energy at the peak of the jump:
$$
U = mgh
$$
We know:
Potential Energy : \( U = 2343.04 \text{ J} \)
Mass of the man : \( m = 60 \text{kg} \)
Acceleration due to gravity : \( g = 9.8 \text{m/s}^2 \)
Now solve for height:
\( h = \frac{U}{m \times g} = \frac {2343.04}{60 \times 9.8} \approx 3.99 \text{m} \)
Step 4: Match to the Correct Answer
From the previous step, the man can jump approximately 4 meters using the energy gained from the mangoes. Thus, the correct answer is: (1) 4 m