The frictional force is too much compared to the gravitational force
Explanation:
This is because of the great amount of frictional force between the book and the wall.
Also, the force of gravity on the book is not high enough to cause motion of the book to slide downs.
Frictional force is a force that opposes motion.
- For the book to slide down, it must overcome the force of friction acting on it opposite to the direction of gravity.
- According to newton's first law 'a body will remain in its state of rest or uniform motion unless acted upon by an external force'.
- Assuming the external force is gravitational force, clearly we see that the force is less than the frictional exerted on the book by pinning it to the wall.
- This frictional force is a static friction that is on a body at rest, it must be overcome by a larger force before motion takes place.
Fr > fg
Fr is the frictional force
fg is the gravitational force
learn more:
Newton laws brainly.com/question/11411375
#learnwithBrainly
The answer to this question is D
Answer:
The second material's index of refraction is 1.17.
Explanation:
Given that,
Refractive index of the material, n = 1.29
Critical angle is 65.9 degrees.
We need to find the second material's index of refraction. We know that at critical angle of incidence, angle of refraction is equal to 90 degrees. Using Snell's law as:

So, the second material's index of refraction is 1.17.
Answer:
0.001 s
Explanation:
The force applied on an object is equal to the rate of change of momentum of the object:

where
F is the force applied
is the change in momentum
is the time interval
The change in momentum can be written as

where
m is the mass
v is the final velocity
u is the initial velocity
So the original equation can be written as

In this problem:
m = 5 kg is the mass of the fist
u = 9 m/s is the initial velocity
v = 0 is the final velocity
F = -45,000 N is the force applied (negative because its direction is opposite to the motion)
Therefore, we can re-arrange the equation to solve for the time:
