Answer:
μ = 0.66, therefore if it compiesy with the regulations
Explanation:
Let's solve this exercise in part, let's start by finding with kinematics the acceleration of man
y = v₀ t + ½ a t²
as it starts from rest the initial velocity is zero
y = ½ a t²
a =
a =\frac{2 \ 4.38}{1.21^2}
a = 6.46 m / s²
Now let's use Newton's second law,
Axis y
N- W = 0
N = W
N = m g
X axis
on this axis the man exerts a backward force and by the law of action and reaction the floor exerts a forward force of the same magnitude, this forward force is the friction force.
fr = m a
the friction force has an expression
fr = my N
let's substitute
μ mg = m a
μ = a / g
let's calculate
μ = 6.46 / 9.8
μ = 0.66
therefore if you comply with the regulations
A=F/m
=5/12
=0.42 m/s^2
Since the ball stops, it decelerates at a rate of 0.42 m/s^2 before stopping and it’s final velocity is 0 m/s.
t=(u-v)/a
=(20-0)/0.42
=48 s
Yes, it did help to change the world climate
for example by the Carbon Dioxide released from factories, Cars and even from respiration
Petroleum products are especially useful as sources of energy because it furnishes a convenient, concentrated source of energy.
So even if it is a tiny degree it can grow and grow into something very big.
For example let’s say you take a measurement of the angle your sofa is and you mistake by a few degrees.No problem!! You will only be a few micro centimetres off.
But if you are a few degrees of in measuring the angle of a nearby star you can be as much as a few million light years off because the angle grows and grows by the time you travel that distance.
So basically even a tiny amount can be catastrophic at a big scale