The sun’s huge mass gives it a strong gravitational pull. Because of this gravitational pull, planets that are closer to the sun tend to have different motion than planets that are further away from the sun, because the gravity becomes stronger the closer you get. I hope this helped!
        
                    
             
        
        
        
We have that for the Question "A 2kg book is held against a vertical wall. The <em>coefficient </em>of friction is 0.45. What is the minimum force that must be applied on the <em>book</em>, perpendicular to the wall, to prevent the book from slipping down the wal" it can be said that  the minimum force that must be applied on the <em>book is</em>
From the question we are told 
A 2kg book is held against a vertical wall. The <em>coefficient </em>of friction is 0.45. What is the minimum force that must be applied on the <em>book</em>, perpendicular to the wall, to prevent the book from slipping down the wal
Generally the equation for the  Force  is mathematically given as

F=44N
Therefore
 the minimum force that must be applied on the <em>book is</em>
F=44N
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Answer:
The near point of an eye with power of +2 dopters, u' = - 50 cm
Given:
Power of a contact lens, P = +2.0 diopters
Solution:
To calculate the near point, we need to find the focal length of the lens which is given by:
Power, P = 
where
f = focal length
Thus
f = 
f =  = + 0.5 m
 = + 0.5 m
The near point of the eye is the point distant such that the image formed at this point can be seen clearly by the eye.
Now, by using lens maker formula:

where
u = object distance = 25 cm = 0.25 m = near point of a normal eye
u' = image distance
Now,



Solving the above eqn, we get:
u' = - 0.5 m = - 50 cm
 
        
             
        
        
        
Answer:
The lose of thermal energy is, Q = 22500 J
Explanation:
Given data,
The mass of aluminium block, m = 1.0 kg
The initial temperature of block, T = 50° C
The final temperature of the block, T' = 25° C
The change in temperature, ΔT = 50° C - 25° C
                                                      = 25° C
The specific heat capacity of aluminium, c = 900  J/kg°C
The formula for thermal energy,
                              <em>Q = mcΔT</em>
                                  = 1.0 x 900 x 25
                                  = 22500 J
Hence, the lose of thermal energy is, Q = 22500 J
 
        
             
        
        
        
Answer:
The ball is dropped at a height of 9.71 m above the top of the window.
Explanation:
<u>Given:</u>
- Height of the window=1.5 m
- Time taken by ball to cover the window height=0.15
Now using equation of motion in one dimension we have

Let u be the velocity of the ball when it reaches the top of the window
then

Now u is the final velocity of the ball with respect to the top of the building
so let t be the time taken for it to reach the top of the window with this velocity

Let h be the height above the top of the window
