Examples on Energy Formula
Example 1: How much work is required to stop the car in 30 s if the kinetic energy of the car is 6000 J and what is its power?
Solution:
Work done to stop car = change in Kinetic energy
W = KE at stop – KE at start
W = 0 – 6000
W = -6000 J (negative sign means work is done against car)
- Time = 30 sec (given)
Power = Work Done /Time = 6000/30 = 200 Watt
Example 2: Two passengers of mass 40 kg each sit in the car then find the Kinetic energy of car if the mass of the car is 700 kg and velocity of the car is 18 km/h.
Solution:
Given,
- Mass of Car = 700 kg
- Mass of Each Person = 40 kg
- Total Mass(m) = 700 + 40 + 40 = 780 kg
- Velocity = 18 kn/hr = 18(5/18) = 5 m/s
KE = 1/2 mv2
KE = 1/2(780)(5)2
KE = 9750 J
Example 3: Find the work done by the 10 N force acting on the object at the angle of 60°, which displaces the object 10 m.
Solution:
Given,
- F = 10 N
- s = 10 m
- θ = 60°
W= F.s.cosθ
cos 60° = 1/2
W = (10).(10).(1/2)
W = 50J
Example 4: 245 × 102 J of work doneto raise a 50 kg boy above the ground. How high would he be raised? (g = 9.8 m.s-2)
Solution:
Given,
- Work Done = 24500 J
- m = 50 kg
- g = 9.8 m.s-2
Work Done = mgh
245 × 102 = 50 × 9.8 × h
h = 50 m
The height at which the boy is raised is 50 m.
Energy
Energy in Physics is defined as the capacity of a body to do work. It is the capacity to complete a work. Energy can be broadly categorized into two categories, Kinetic Energy and Potential Energy. The capacity of an object to do the work is called the Energy. In this article, we will learn about, Energy, Types, of Energy, the Law of conservation of Energy, and others in detail.
Before learning about energy, we must first learn about, Work Done, so let’s start with the same.
Table of Content
- What Is Energy?
- Units of Energy
- Energy Conversion: Transfer and Transform
- Law of Conservation of Energy
- Different Types of Energy
- Work-Energy Theorem