The answer is A. Minutes per gallon, because the independent quantity is the gallons
In order to build a hypothesis, Joan should take an educated guess at what the effect of adding salt to the water will be on the water's boiling point. For example, the hypothesis may be,"The boiling point will increase". This hypothesis is one that can be verified or rejected via experimentation. The next step for Joan would be to set up an experiment to test this hypothesis.
Answer:
The velocity with which the mass will hit the floor is 
Explanation:
If the tension in the string is 
, for 
we have
,
and for the mass 
From these equations we solve for 
and get:
The kinematic equation
gives the final velocity 
of a particle, when its initial velocity was 
, and has traveled a distance 
while undergoing acceleration .
In our case
(the initial velocity of the particles is zero)
which gives us
which is the velocity with which the mass will hit the floor.
Momentum = (mass) x (speed)
Change in momentum = (force) x (time)
The initial momentum is (mass) x (speed) = 2500x 25 = 62,500 kg-m/s.
Since you want to <u>stop</u> the vehicle, that number is also the required <em>change</em>
in momentum ... you want the vehicle to wind up with zero momentum.
62,500 = (force) x (time) = 20 x force
Divide each side by 20 :
force = 62,500 / 20 = <em>3,125 newtons </em>
