Answer:
fr = m v₀² / 2 (x₁-x₀)
Explanation:
a) For this exercise we use Newton's second law
X axis
- fr = ma
Y Axis
N-W = 0
N=W
let's look for acceleration with expressions of kinematics
v² = v₀² - 2 a Δx
at the point where stop v = 0
a = v₀² / 2 Δx
let's replace
-fr = m (- v₀² / 2 (x₁-x₀))
fr = m v₀² / 2 (x₁-x₀)
b)they ask for the same
in this case part of rest
v₁² = 0 + 2 a Δx
a = v₁² / 2ΔX
we write Newton's second law
F - fr = m a
fr = F - ma
fr = F - m v₁² / 2Δx
Answer:
4.0 m/s
Explanation:
In the first part of the run, the athlete runs a distance of
at a speed of
So, the time he/she takes is
In the second part of the run, the athlete covers an additional distance of
with a speed
So, the time taken in this second part is
So, the total distance covered is
d = 300 m + 300 m = 600 m
And the total time taken
t = 100 s + 50 s = 150 s
Therefore, the average speed for the entire trip is
Answer:
20m/s
Explanation:
it covers 20 metres in a second
Power<span> is the rate of doing work. It is the amount of energy consumed per unit time. Having no direction, it is a scalar quantity. We express it as follows:
P = W / t
where W = Fd
F = mg
Therefore,
P = mgd / t
P = (30)(9.81)(20) / 1 = 5886 W</span>
