The frictional force will be 0.22N.
<h3>What is Frictional force?</h3>
Frictional force is the force generated between two surfaces that are in contact and slide against each other.
Given,
Weight=4N
mass =4.9/9.8=0.5kg
Hieght =30m
velocity=24m/s
Acceration , v²-u²=2as
24²/2×30 =a , u is zero
a= 1.5m/s²
By Using conservation of energy ,
30F+1/2mv²=mgh
30F=1150-144
F= 6/30
F=0.2N
The force will be 0.2N
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To solve this problem we will apply the linear motion kinematic equations. To determine the position in which the braking starts we will start from the definition of distance as a function of speed and time, that is
Here,
= Initial position
v = Velocity
t = time
Replacing we have that
Now the acceleration is given by the function,
Here,
= Final velocity
= Initial velocity
a = Acceleration
x = Displacement
Replacing we have that
Therefore the acceleration necessary to bring the train to rest is
Answer: b
. Natural selection is a process that brings about evolution
Explanation:
The natural selection can be defined as the differential survival and reproduction of the organisms that have better phenotypic traits which allow them to survive in their changing environment. These traits are passed on to the next generation this process is necessary for the evolution of the species. The evolution is the change in the structure and function of the organisms with the passage of them.