Download Understanding Kinetic Energy: Equations, Calculations, and Examples and more Exams Reasoning in PDF only on Docsity!
Kinetic energy
- Investigate examples of kinetic energy.
- Calculate the kinetic energy, mass, or velocity of an object using the kinetic energy equation.
- Employ proportional reasoning to predict the effect of mass and velocity changes on the kinetic energy of an object. kinetic energy kinetic en
Objectives
- What does each of the symbols mean in this equation: Ek = ½ mv^2?
- Translate the equation Ek = ½ mv^2 into a sentence with the same meaning.
- How much kinetic energy does a 1.0 kg mass have when traveling at a speed of 30 m/s? At twice this speed?
- How fast would a 2.0 kg mass have to be moving to have a kinetic energy of 1,000 J?
- What is the mass of an object that has a kinetic energy of 500 J and a speed of 25 m/s?
Assessment Physics terms
- kinetic energy
- mechanical energy
Equations
The kinetic energy of a moving object is one half of the product of its mass multiplied by the square of its velocity. or It depends on the mass of an object, and its speed.
Energy of motion
Kinetic energy is energy due to motion.
A 1 liter water bottle (1 kg) moving at 1 m/s (2.4 mph) has a kinetic energy of... Energy of motion
Kinetic energy is energy due to motion.
Energy of motion
Kinetic energy is energy due to motion.
A 1 liter water bottle (1 kg) moving at 1 m/s (2.4 mph) has a kinetic energy of 0.5 joules. Click the interactive calculator on page 258. Exploring the ideas Engaging with the concepts
Kinetic energy 10 What is the kinetic energy of a 1.0 kg object moving at 10 m/s? Engaging with the concepts
Kinetic energy 10 What is the kinetic energy of a 1.0 kg object moving at 10 m/s? 50 joules Click [Run] to see the motion. 50 Engaging with the concepts
Kinetic energy 10000 Suppose a 10 gram marble is traveling at 10,000 m/s— a typical speed for space debris orbiting the Earth. What is the kinetic energy of the marble?
Engaging with the concepts
What happens to the kinetic energy of an object if you double its mass? triple its mass? Try it and see. Kinetic energy
Engaging with the concepts
What happens to the kinetic energy of an object if you double its velocity? triple its velocity? Try it and see. Kinetic energy
The kinetic energy increases as the square of the speed. Calculating kinetic energy The kinetic energy increases as the square of the speed. If the speed triples, how does the kinetic energy change? Calculating kinetic energy The kinetic energy increases as the square of the speed. If the speed triples, how does the kinetic energy change? Calculating kinetic energy 32 = 9 The kinetic energy increases by a factor of 9. A cart has 10 joules of kinetic energy. If its mass doubles AND its velocity doubles, how much kinetic energy does it have? Test your knowledge
A cart has 10 joules of kinetic energy. If its mass doubles AND its velocity doubles, how much kinetic energy does it have? Eight times as much: 80 joules Test your knowledge Where does this equation come from? Deriving the formula Deriving the formula Hypothesis: The kinetic energy of an object equals the work done to change its velocity from zero to v. Work is force times distance. Deriving the formula Work is force times distance. Deriving the formula We need an expression for d. Work is force times distance. Deriving the formula This is the distance d traveled at constant acceleration: We need an expression for d.
Assessment
- What does each of the symbols mean in this equation: Ek = ½ mv^2? Assessment 1. What does each of the symbols mean in this equation: Ek = ½ mv^2? Ek (or KE ) = kinetic energy in joules m = mass in kg v = speed in m/s Assessment
- What does each of the symbols mean in this equation: Ek = ½ mv^2? Ek (or KE ) = kinetic energy in joules m = mass in kg v = speed in m/s
- Translate the equation Ek = ½ mv^2 into a sentence with the same meaning.
- What does each of the symbols mean in this equation: Ek = ½ mv^2? Ek (or KE ) = kinetic energy in joules m = mass in kg v = speed in m/s
- Translate the equation Ek = ½ mv^2 into a sentence with the same meaning. Assessment The kinetic energy of an object is one half of the product of its mass multiplied by the square of its velocity. Assessment
- How much kinetic energy does a 1.0 kg mass have when traveling at a speed of 30 m/s? Assessment
- How much kinetic energy does a 1.0 kg mass have when traveling at a speed of 30 m/s? Ek = ½ mv^2 = ½ (1 kg)(30 m/s)^2 = 450 J
- How much kinetic energy does a 1.0 kg mass have when traveling at a speed of 30 m/s? Assessment How much kinetic energy does the mass have when traveling at twice this speed? Ek = ½ mv^2 = ½ (1 kg)(30 m/s)^2 = 450 J Assessment Four times as much: Ek = 4 (450J) = 1800 J
- How much kinetic energy does a 1.0 kg mass have when traveling at a speed of 30 m/s? How much kinetic energy does the mass have when traveling at twice this speed? Ek = ½ mv^2 = ½ (1 kg)(30 m/s)^2 = 450 J
- How fast would a 2.00 kg mass have to be moving to have a kinetic energy of 1,000 J? Assessment Assessment
- How fast would a 2.00 kg mass have to be moving to have a kinetic energy of 1,000 J? Assessment
- How fast would a 2.00 kg mass have to be moving to have a kinetic energy of 1,000 J? Method 2: Assessment
- How fast would a 2.00 kg mass have to be moving to have a kinetic energy of 1,000 J? Method 2:
