Answer:
- Binary
- Open cluster
- Globular cluster
Explanation:
A star system is a group of stars that orbit one another, through he influence of gravitational force. The Earth's star system is called solar system.
B
Force=Mass times acceleration
15=3x
x=5ms^2
Answer:
20 J
Explanation:
Given:
Weight of the book is, 
Height or displacement of the book is, 
The work done on the book to raise it to a height of 2 m on a shelf is against gravity. The gravitational force acting on the book is equal to its weight. Now, in order to raise it, an equal amount of force must be applied in the opposite direction.
So, the force applied by me should be equal to weight of the body and in the upward direction. The displacement is also in the upward direction.
Now, work done by the applied force is equal to the product of force applied and displacement of book in the direction of the applied force.
Therefore, work done is given as:

Therefore, the work done to raise a book to a height 2 m from the floor is 20 J.
Answer: elastic potential energy
Explanation: