The boulder has a weight of W=2400 N. The weight of an object is the product between its mass m and the gravitational acceleration g:

Rearranging the relationship, we can calculate the mass of the boulder:

We are told that Superman applies a horizontal force to this object, and as a result, the acceleration of the boulder is

. We can find the force applied by using Netwon's second law of motion:
Answer:
15 N and 3.061
Explanation:
From the question,
The minimum force of friction to keep the book from sliding = 15 N.
using
F = mgμ................. Equation 1
Where F = Frictional Force, m = mass of the book, g = acceleration due to gravity, μ = coefficient of friction.
make μ the subject of the equation
μ = F/mg............... Equation 2
Given: F = 15 N, m = 0.5 kg, g = 9.8 m/s²
Substitute into equation 2
μ = 15(0.5×9.8)
μ = 15/4.9
μ = 3.061
Hence the coefficient of friction to keep the book from sliding = 3.061
Answer: <em>One main reason, all three experts agree, is the phenomenon known as “windthrow” which uproots a tree. “The tree trunk acts as a lever and so the force applied to the roots and trunk increases with height,” says Foster. “Taller trees are more susceptible to windthrow.”</em>
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The time taken for the plant to hit the ground from a distance of 7.01m and at a velocity of 8.84m/s is 1.59s.
<h3>How to calculate time?</h3>
The time taken for a motion to occur can be calculated using the following formula:
v² = u² - 2as
Where;
- v = final velocity
- u = initial velocity
- s = distance
- a = acceleration
8.84² = 0² + 2 × a × 7.01
78.15 = 14.02a
a = 5.57m/s²
V = u + at
8.84 = 0 + 5.57t
t = 1.59s
Therefore, the time taken for the plant to hit the ground from a distance of 7.01m and at a velocity of 8.84m/s is 1.59s.
Learn more about time at: brainly.com/question/13170991
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