Answer:
559.5 N
Explanation:
Applying,
v² = u²+2gs............. Equation 1
Where v = final velocity,
From the question,
Given: s = 5.10 m, u = 0 m/s ( from rest)
Constant: 9.8 m/s²
Therefore,
v² = 0²+2×9.8×5.1
v² = 99.96
v = √(99.96)
v = 9.99 m/s
As the diver eneters the water,
u = 9.99 m/s, v = 0 m/s
Given: t = 1.34 s
Apply
a = (v-u)/t
a = 9.99/1.34
a = -7.46 m/s²
F = ma.............. Equation 2
Where F = force, m = mass
Given: m = 75 kg, a = -7.46 m/s²,
F = 75(-7.46)
F = -559.5 N
Hence the average force exerted on the diver is 559.5 N
Answer:
It's option d - Negative acceleration
Explanation:
- Let's start by demonstrate why <em>it's not option b - Speed : </em>Speed is a scalar quantity so it can not be represented by a vector
- Let's check that <em>the green vectors represent velocity</em> (velocity is a vector quantity, velocity is a direction aware, while speed is just a scalar)
- Now let's show that the circled vectors are acceleration vectors:
Mathematically position X , velocity V and acceleration A are:
and 
Where X, V, A are vectors and 
indicates the derivate a of a time is equal to b.
So, this show that acceleration is a rate respect of time of velocity ⇒ When acceleration is positive, velocity increments, when acceleration is negative, velocity decrements.
<em>The above explanation correspond to the motion map shown, getting demonstrated that the answer is D - Negative acceleration </em>
The answer is B as all the other options contain quantities not related to describing motion
I'm happy to know that the diagram shows how it's all set up.
If I could see the diagram, then I could probably do a much
better job with an answer. As it is ... 'flying blind' as it were ...
I'm going to wing it and hope it's somewhat helpful.
If the pulley is movable, then I'm picturing one end of the rope
tied to a hook in the ceiling, then the rope passing down through
the pulley, then back up, and you lifting the free end of the rope.
A very useful rule about movable and combination pulleys is:
the force needed to lift the load is
(the weight of the load)
divided by
(the number of strands of rope supporting the load) .
With the setup as I described it, there are 2 strands of rope
supporting the load ... one on each side of the pulley. So the
force needed to lift the load is
(250 N) / 2 = 125 N .
