Mass of the object m = 25 kg
Coefficient of friction Uk = 0.15
Frictional force Ff = Uk x F => Ff = Uk x m x g
Ff = 0.15 x 25 x 9.8
Frictional Force Ff = 36.75 N
<h3>Question:</h3>
How to find g (acceleration due to gravity)
<h3>Solution:</h3>
We know,
Acceleration due to gravity (g)

where, G = Gravitational constant

M = Mass of the earth

R = Radius of the earth

Putting these values of G, M and R in the above formula, we get

So, the value of acceleration due to gravity is

Hope it helps.
Do comment if you have any query.
Answer:
Net force will be 4.875 N
Explanation:
We have given mass of the cart m = 1.5 kg
Initial velocity of the cart = 0.2 m/sec
And final velocity of the car = - 0.125 m/sec ( Negative direction is due to opposite direction )
Instant of time 
Change in momentum is given by

Now force is given by

Net force will be 4.875 N
Answer:
The magnitude of F₁ is 3.7 times of F₂
Explanation:
Given that,
Time = 10 sec
Speed = 3.0 km/h
Speed of second tugboat = 11 km/h
We need to calculate the speed


The force F₁is constant acceleration is also a constant.

We need to calculate the acceleration
Using formula of acceleration



Similarly,

For total force,


The speed of second tugboat is


We need to calculate total acceleration



We need to calculate the acceleration a₂



We need to calculate the factor of F₁ and F₂
Dividing force F₁ by F₂



Hence, The magnitude of F₁ is 3.7 times of F₂
Eventually wouldn't it collapse in on itself and create black hole.