the formula for velocity is:
v= distance/time
distance= 80m
time=2 seconds
v=80/2
v=40ms-1
<span>Newton's law of gravitation is attractive, whereas Coulomb's law is attractive or repulsive. Both are proportional to the inverse square of distance.</span>
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
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The work done was done by friction to keep the crate from moving as the truck came to a stop is 20,000 J.
<h3>
Work done by friction to prevent the crate from moving</h3>
The work done is determined by applying the principle of conservation of energy.
W = K.E
W = ¹/₂mv²
where;
- m is mass of crate
- v is speed of the crate with respect to the truck = 20 m/s
W = ¹/₂(100)(20²)
W = 20,000 J
Thus, the work done was done by friction to keep the crate from moving as the truck came to a stop is 20,000 J.
Learn more about work done here: brainly.com/question/8119756
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