Answer:d
Explanation:
Drift velocity is given by
where =drift velocity
I=Current
n=no of electron
Q=charge of Electron
A=cross-section
If area of cross-section decreases gradually then drift velocity will increase because drift velocity is inversely proportional to Area of cross-section
Answer:
m = 236212 [kg]
Explanation:
The potential energy can be determined by means of the product of mass by gravity by height. In this way, we have the following equation.
where:
P = potential energy = 3360000000 [J]
m = mass [kg]
g = gravity acceleration = 9.81 [m/s²]
h = elevation = 1450 [m]
Now, we can clear the mass from the equation above:
Answer
(C).
When there is an angle between the two directions, the cosine of the angle must be considered.
Step by step Solution
The work done by a force is defined as the product of the force and the distance traveled in the direction of motion.
The first answer "Only the component of the force perpendicular to the motion is used to calculate the work" is wrong because, the force perpendicular to motion does no work.
The second choice "If the force acts in the same direction as the motion, then no work is done" is wrong because the work in the direction of the force is .
Fourth answer "A force at a right angle to the motion requires the use of the sine of the angle" is wrong because the meaning that there is no work done in the direction perpendicular to the motion.
The third answer" When there is an angle between the two directions, the cosine of the angle must be considered." is correct because the work is calculated using the force in the direction of the motion. The magnitude of this force is
We use the formula,
.
Here, v is velocity and its value given 26 mi/h ( in m/s, ) and d is distance and its value is given 80 m.
Substituting these values in above formula we get,
Thus, the time delay between green lights on successive blocks to keep the traffic moving continuously is 6.88 s