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: 
Explanation:
IMA stands for Ideal Mechanical advantage.
The IMA of pulley system can be defined as the ratio of output force to input force.
From the given pulley system,
The input force = 
The output force = 
Hence, IMA of the given pulley system,

Answer:
Sonia's grandfather was not able to see clearly after returning from his walk on a bright sunny day. He was about to hit a chair when Sonia held him and guided him to the nearby sofa, in sunny environment grandfather's eye is set according to high brightness, his pupils become small to lower the number of light rays entering his eye, when he returned from sunny environment to his house which was having low brightness so the pupils should enlarge to absorb more light to see clearly but due to old age his Ciliary muscle of the eye would have worn out and due to this poor coordination the image was not clear.
Explanation:
using the formula: S=ut+½gt², where u=0, S=?, g=8m/s², t=10seconds.
S=ut+½gt² ("ut" term will cancel because u=0).
=> S= ½gt²
=>S = ½×8×10²
=>S = 4×100
=>S = 400m .
Therefore, the distance traveled by the body in 10s is 400m.
hope this helps you.
<span>the answer would be 3,959 miles</span>