Answer:
14 m/s
Explanation:
The motion of the book is a free fall motion, so it is an uniformly accelerated motion with constant acceleration g=9.8 m/s^2 towards the ground. Therefore we can find the final velocity by using the equation:

where
u = 0 is the initial speed
g = 9.8 m/s^2 is the acceleration
d = 10.0 m is the distance covered by the book
Substituting data, we find

Answer: a = 1.32m/s2
Therefore, the average acceleration is 1.32m/s2
Explanation:
Acceleration is the rate of change in the velocity per time
a = change in velocity/time
a = ∆v/t
average acceleration a = (v2 -v1)/t. ....1
Given;
Final velocity v2 = 1.63m/s
Initial velocity v1 = -1.15ms
time taken t = 2.11s
Substituting into eqn 1
a = [1.63 - (-1.15)]/2.11
a = (1.63+1.15)/2.11
a = 2.78/2.11
a = 1.32m/s2
Therefore, the average acceleration is 1.32m/s2
Answer:
<em>The second option has a lower power output. P=30 W</em>
Explanation:
<u>Mechanical Power
</u>
It is a physical magnitude that measures the rate a work W is done over time t.

Since W=F.d

The first option means the worker will lift the box by a distance of 1.2 meters in 3 seconds by applying 250 N of force. That produces a power of

The second option requires the worker applies 75 N of force and travel a distance of 4 meters for 10 seconds, thus the power is

The second option has a lower power output