Answer:
Yes we can find the initial velocity of car without finding acceleration.
u = 10 m/s.
Explanation:
Given that
s=20 m
Car takes 4 s to come in rest.
We know that when acceleration is constant then we can apply motion equation
----------1
------2
From equation 1 and 2

So we can say that

Given that the velocity of car at final condition will be zero (v=0)


From the above equation we can find the initial velocity of car without finding the acceleration

u = 10 m/s
Answer:
The weight of Earth's atmosphere exert is 
Explanation:
Given that,
Average pressure 
Radius of earth 
Pressure :
Pressure is equal to the force upon area.
We need to calculate the weight of earth's atmosphere
Using formula of pressure


Where, P = pressure
A = area
Put the value into the formula


Hence, The weight of Earth's atmosphere exert is 
The average speed can be easily calculated by taking the
ratio of distance and time. That is:
average speed = distance / time
so calculating:
average speed = 4875 ft / 6.85 minutes
<span>average speed = 711.68 ft / min</span>
To solve this problem it is necessary to apply the concepts related to thermal stress. Said stress is defined as the amount of deformation caused by the change in temperature, based on the parameters of the coefficient of thermal expansion of the material, Young's module and the Area or area of the area.

Where
A = Cross-sectional Area
Y = Young's modulus
= Coefficient of linear expansion for steel
= Temperature Raise
Our values are given as,




Replacing we have,


Therefore the size of the force developing inside the steel rod when its temperature is raised by 37K is 38526.1N