A Dodge Stealth is driving at 70 mph on a highway. It passes a BMW going the same direction. The BMW is moving 7 mph backward re
1 answer:
A Dodge Stealth is driving at 70 mph on a highway. It passes a BMW going the same direction. The BMW is moving 7 mph backward relative the Dodge. 63 mph is the velocity of the BMW
Answer: Option A
<u>Explanation:</u>
Given is the speed of the dodge stealth as 70 mph passing by the BMW moving with 7 mph relative to Dodge. Thereby, to calculate the velocity of BMW, relative velocity concept has to be employed.
As we know that the relative velocity tells us about relative velocity of mobile reference system as the difference or sum of the initial reference system.
Therefore,
velocity of the BMW =
Velocity of the dodge =
Velocity of the BMW with respect to dodge =
As per the formula,
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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.
For this case we have that by definition, the kinetic energy is given by the following formula:
Where:
m: It is the mass
v: It is the velocity
According to the data we have to:
Substituting the values we have:
finally, the kinetic energy is
Answer:
Option A