Answer:
20m/s
Explanation:
acceleration=final velocity-initial velocity/time
4.0m/s²=v m/s-0m/s/5.0sec
5.0sec×4.0m/s²=v m/s-0m/s×5.0m/s/5.0m/s
20m/s=v
(a) Let's convert the final speed of the car in m/s:

The kinetic energy of the car at t=19 s is

(b) The average power delivered by the engine of the car during the 19 s is equal to the work done by the engine divided by the time interval:

But the work done is equal to the increase in kinetic energy of the car, and since its initial kinetic energy is zero (because the car starts from rest), this translates into

(c) The instantaneous power is given by

where F is the force exerted by the engine, equal to F=ma.
So we need to find the acceleration first:

And the problem says this acceleration is constant during the motion, so now we can calculate the instantaneous power at t=19 s:
To find out the kinetic friction, using the coefficient friction formula.
What is kinetic friction?
A force that acts between moving surfaces is called "kinetic friction." A force acting in opposition to the direction of a moving body on the surface is felt. The two materials' kinetic friction coefficients will determine how much force is applied.
What is coefficient friction?
A measure of the degree of friction between two surfaces is the coefficient of friction. A coefficient of friction is determined by calculating the resistance to motion at the intersection of two surfaces made of the same or different materials.
UK
U-coefficient of friction
K-Kinetic friction
Using UK
450+370-f=m*o
f=820=UK*260*9.8
UK=2.548
820/2.548
UK= 321.8210361
Therefore the coefficient of kinetic friction is 321.8210361
Learn more about Kinetic friction from the given link.
brainly.com/question/14111192
#SPJ4
Answer:
F = 326.7 N
Explanation:
given data
mass m = 200 kg
distance d = 2 m
length L = 12 m
solution
we know force exerted by the weight of the rock that is
W = m × g ..............1
W = 200 × 9.8
W = 1960 N
and
equilibrium the sum of the moment about that is
∑Mf = F(cos∅) L - W (cos∅) d = 0
here ∅ is very small so cos∅ L = L and cos∅ d = D
so F × L - W × d = 0 .................2
put here value
F × 12 - 1960 × 2 = 0
solve it we get
F = 326.7 N