Question

2 Physics Questions WILL GIVE BRAINLIEST!!

A book is being pushed along a table at a constant speed. The coefficient of static friction is 0.75, and the coefficient of kinetic friction is 0.30. The book has a mass of 0.50 kg. What is the force of friction?

0.15 N
1.5 N
3.7 N
0.38 N

Suppose the mass of each of two spherical objects is doubled, and the distance between their centers is three times as large. How is the magnitude of the force of gravity between them affected?

It is 4/9 as large
It is 3/2 as large
It is 4/3 as large
It is 2/3 as large
It is 2/9 as large

Answer 1

Answer:

a) The force of friction is 1.5 N.

b) The new force is 4/9 times as large as the original force.

Explanation:

It is given that the book is moving on the table.

∴ The friction acting on the block should be kinetic.

∴ Coeffecient of kinetic friction , k = 0.3

The force of friction = kN , where 'N' is the normal force acting on the surface where friction is acting.

In this case , N = mg , where 'm' is the mass of the book and 'g' is the acceleration due to gravity.

∴ Force of friction , f = kmg = 0.3×0.5×10 = 1.5N

b) We know that ,

Gravitational force , F ∝ m  , where 'm' is the mass of the body.

                                 F ∝ $x^{2}$ where 'x' is the distance between the      two bodies.

Since mass of both the bodies is doubled , the force will be 4 times as large compared to the original force F from the first proportionality equation.

However , as the distance is 3 times as large , the force will be 9 times as small as compared to the original force F

∴ The new force is 4/9 times as large as the old force