Answer:
d) What is the force if we doubled both the masses AND we doubled the distance
Answer:
The speed decreases.
Explanation:
This can be explained using the conservation of linear momentum.
Since there is no friction, the initial moment of the train must be equal to its linear moment after it is filled with water.
the initial linear momentum is

where
is the initial mass of the train, and
the initial speed of the train.
And linear momentum after the water filled the train car is

where
is mass of the train after the rain, and
the speed of the train after the rain
<u>the equality must be fulfilled:</u>

We know that if water is added to the train,
that is the mass after the water is added, is greater than
which is the mass of the train without the water.
Therefore, in order for the conservation of the linear momentum to be fulfilled: 
the speed after the water is added (
) must be smaller than the initial train speed (
) . So the speed of the car decreases.
Oooooo there's a spongy bone? that's cool! Lol okay okay, I will research it and help you out.
Here's what I found:
Cancellous bone<span>, also known as </span>spongy<span> or </span>trabecular bone<span>, is one of the </span>two<span> types of </span>bone<span> tissue found in the human body. ... It is very porous and contains red </span>bone<span>marrow, where blood cells are made.</span>
It is an example of balanced force.
hope this helps. good luck
Answer:
1 W = 1 J / sec Definition of watt is 1 joule / sec
So if a bulb uses 75 J / sec it must use
75 J/s * 60 sec / min = 4500 J/min energy used by bulb
If bulb is 15% efficient then the light delivered is
P = 4500 J / min * .15 = 675 J / min