Advertisements
Advertisements
Question
The weight of a person on planet A is about half that on the earth. He can jump up to 0.4 m in height on the surface of the earth. How high he can jump on planet A?
Advertisements
Solution
The weight of a person on a planet is half that on the earth,
WA = `1/2 "W"_"E"`
or mgA = `1/2 "mg_E"`
or `"g"_A = 1/2 "g"_E`
Now, as the person jumps, gain in potential energy remains the same.
So, mgAhA = mgE hE
∴ `"h"_A = ("g"_"E""h"_"E")/"g"_"A"`
= `("g"_"E" xx 0.4"m")/("g"_E/2)` (Using (I) nd hE = 0.4 m)
= 0.8m
(Using (i) and hE = 0.4 m)
APPEARS IN
RELATED QUESTIONS
Write true or false of the following statement.
In an electric fan, electrical energy changes into the mechanical energy.
Fill in the blank
An electric fan converts electrical energy into ______ energy.
Fill in the blank
The S.I.unit of energy is ______
Match the following columns
| COLUMN A | COLUMN B |
| 1. Running water | 1. heat energy |
| 2. Burning | 2. vibrations |
| 3.Energy | 3.atom bomb |
| 4.Sound energy | 4.kinetic energy |
| 5.Nuclear energy | 5.joule |
Define the term efficiency of a machine.
Name two units of power bigger than watt.
- Take two aluminium channels of different lengths.
- Place the lower ends of the channels on the floor and hold their upper ends at the same height.
- Now take two balls of the same size and weight and release them from the top end of the channels. They will roll down and cover the same distance.
- At the moment of releasing the balls, which energy do the balls have?
- As the balls roll down which energy is converted into which other form of energy?
- Why do the balls cover the same distance on rolling down?
Note: The question is wrong. It should be "Why do the balls cover the same distance after rolling down"? - What is the form of the eventual total energy of the balls?
- Which law related to energy does the above activity demonstrate? Explain.
We make useful objects from a variety of substances. Another use of substances is that we get energy from some of them.
There is a car. Its tank is full of fuel but it does not move. Why is that?
Running water possesses ______.
When a body falls freely towards the earth, then its total energy
