There are some missing data in the text of the problem. I've found them online:
a) coefficient of friction dry steel piston - steel cilinder: 0.3
b) coefficient of friction with oil in between the surfaces: 0.03
Solution:
a) The force F applied by the person (300 N) must be at least equal to the frictional force, given by:

where

is the coefficient of friction, while N is the normal force. So we have:

since we know that F=300 N and

, we can find N, the magnitude of the normal force:

b) The problem is identical to that of the first part; however, this time the coefficienct of friction is

due to the presence of the oil. Therefore, we have:
Close the switch would be the correct answer
Answer:
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Explanation:
4 degrees C turns out to be the temperature at which liquid water has the highest density. If you heat it or cool it, it will expand. ... Ice floats on top of lakes, preventing evaporation (and convection in the frozen layer), and lakes stay liquid underneath, allowing fish and other life to survive.
Answer:
Average speed of the car A = 70 miles per hour
Average speed of the car B = 60 miles per hour
Explanation:
Average speed of the car A is
(Equation A) and Average speed of the car B is
(Equation B), where
and
are the distances and
and
are the times at which are travelling the cars A and B respectively.
We have to convert the time to the correct units:
1 hour and 36 minutes = 96 minutes

From the diagram (Please see the attachment), we can see that at the time they meet, we have:
(Equation C)
(Equation D)
From Equation A and C, we have:

208-x+16 = x
208 + 16 = 2x

x = 112 miles
Replacing x in Equation A:


Replacing x in Equation B:


