Answer:
We know from the basic speed distance relation that

Since the car started from rest and it covered the distance between the 2 officer's in 19 minutes we have speed of the car

Which clearly exceeds the limit of 
The answer is wheel and axle
The density, hard, strong, and rough.
Answer:
Mg and HCl
Explanation:
Here, we want to get the combination that could be used in the production of the needed hydrogen
An important chemical property of inorganic acids is that when they react with metals, they give off hydrogen gas in conjunction with the formation of a salt
HCl is a mineral acid while Mg is a metallic substance
So the reaction between this metal and the mineral acids will give the needed hydrogen gas to be produced
So we want to explain the effects of time dilation. In theory of relativity time dilation is the difference of elapsed time between two events when measured by two observers who are moving relatively to each other. A clock of an observer that is standing still in an inertial frame of reference is going to measure a different time of an event than the clock of an observer that is moving with some velocity with respect to the inertial reference frame that is not moving. In a nutshell, the moving clock is ticking slower than the clock that is standing still.