Answer:
A - 0 N
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Answer:
a. be sure to hold expansion cards by the edge connectors
Explanation:
Removal of loose jewelry is a good safety practice. Also not touching a microchip with a magnetized screwdriver is also a good practice.
But holding expansion cards by the edge connectors is not a good practice, so it is the odd one in the question. Therefore answer option a provides the correct and best answer to the question
Answer:
(a) t = 1.14 s
(b) h = 0.82 m
(c) vf = 7.17 m/s
Explanation:
(b)
Considering the upward motion, we apply the third equation of motion:

where,
g = - 9.8 m/s² (-ve sign for upward motion)
h = max height reached = ?
vf = final speed = 0 m/s
vi = initial speed = 4 m/s
Therefore,

<u>h = 0.82 m</u>
Now, for the time in air during upward motion we use first equation of motion:

(c)
Now we will consider the downward motion and use the third equation of motion:

where,
h = total height = 0.82 m + 1.8 m = 2.62 m
vi = initial speed = 0 m/s
g = 9.8 m/s²
vf = final speed = ?
Therefore,

<u>vf = 7.17 m/s</u>
Now, for the time in air during downward motion we use the first equation of motion:

(a)
Total Time of Flight = t = t₁ + t₂
t = 0.41 s + 0.73 s
<u>t = 1.14 s</u>
The gravitational potential energy U is defined as the product of mass m, the acceleration of gravity g and the height of object h.

We do not have the mass of the hiker. But we know that its W weight is:

Where

So:
.
So:

J
The hiker has gained 30,000 J of energy