Answer:
The resistance that will provide this potential drop is 388.89 ohms.
Explanation:
Given;
Voltage source, E = 12 V
Voltage rating of the lamp, V = 5 V
Current through the lamp, I = 18 mA
Extra voltage or potential drop = 12 V - 5 V = 7 V
The resistance that will provide this potential drop (7 V) is calculated as follows:
Therefore, the resistance that will provide this potential drop is 388.89 ohms.
Answer:
At the point of dropping the object, by Newton's first law due to gravitational force = m × g, accelerates
By Newton's Second law the object reaches impacts on the air with the gravitational force resulting in changing momentum of m×(Final Velocity - Initial Velocity)
As the velocity increases, the rate of change of momentum becomes equivalent to the gravitational force and by Newton's third law, the action action and reaction are equal and opposite hence they cancel each other out
The body then moves at a constant uniform motion down according to Newton's first law
Explanation:
At the point the object of mass, m, is dropped from the height of the tower, the only force acting on the object is the gravitational force such that the object has an acceleration which is the acceleration due to gravity, g, and the gravitational force is therefore = m × g
As the speed of the object increases while the object is falling with the gravitational acceleration the rate at which the object cuts through layers of air which (by Newton's first law of motion, are at rest ) has some buoyancy effect also increases therefore, the object is constantly increasingly changing the momentum of the air which by Newton's second law results, at an high enough velocity, and by Newton's third law, in a force equal to the applied gravitational force
Therefore, the force of the air drag becomes equal to the gravitational force, cancelling each other out and the object then moves according to Newton;s first law, in uniform motion of a constant speed while still falling down.
Average force on the window: 0.32 N
Explanation:
The average force exerted on the window is given by Newton's second law
where
is the net change in momentum of the hailstones in a time interval of
In order to find the change in momentum, we have to consider only the component of the hailstone's momentum perpendicular to the window, therefore:
is the initial momentum of one hailstone, with
m = 7 g = 0.007 kg is the mass
is the initial speed
is the angle with the window
The final momentum is
where
v = 4.5 m/s is the final speed (the collision is elastic so the speed is equal, while the direction changes)
(after the rebound, the direction has changed)
So the change in momentum of 1 hailstone is
We are interested only in the magnitude, so
There are 595 hailstones hitting the window in 49 s, so the total change in momentum is
And therefore, the average force on the window is
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