How many joules of energy are required to run a 100 W light bulb for one day?
<span><span><span>A</span><span>100 </span>joules</span><span><span>B</span>100<span>W </span><span>× </span>24<span>hr </span>joules</span><span><span>C</span>100<span>W </span><span>× </span>24<span>hr </span><span>× </span>60<span>min∕hr </span>joules</span><span><span>D</span>100<span>W </span><span>× </span>24<span>hr </span><span>× </span>60<span>min∕hr </span><span>× </span>60<span>s∕min </span>joules</span></span>
a) 2.75 s
The vertical position of the ball at time t is given by the equation

where
h = 4 m is the initial height of the ball
u = 12 m/s is the initial velocity of the ball (upward)
g = 9.8 m/s^2 is the acceleration of gravity (downward)
We can find the time t at which the ball reaches the ground by substituting y=0 into the equation:

This is a second-order equation. By solving it for t, we find:
t = -0.30 s
t = 2.75 s
The first solution is negative, so we discard it; the second solution, t = 2.75 s, is the one we are looking for.
b) -15.0 m/s (downward)
The final velocity of the ball can be calculated by using the equation:

where
u = 12 m/s is the initial (upward) velocity
g = 9.8 m/s^2 is the acceleration of gravity (downward)
t is the time
By subsisuting t = 2.75 s, we find the velocity of the ball as it reaches the ground:

And the negative sign means the direction is downward.
Answer:
306500 N/C
Explanation:
The magnitude of an electric field around a single charge is calculated with this equation:

With ε0 = 8.85*10^-12 C^2/(N*m^2)
Then:

E(0.89) = 306500 N/C
Answer:
c) It increases by a factor of 8
Explanation:
According to Faraday's law (and Lenz' law), the induced EMF is given as the rate of change of magnetic flux.
Mathematically:
V = -dФ/dt
Magnetic flux, Ф, is given as:
Ф = BA
where B = magnetic field strength and A = Area of object
Hence, induced EMF becomes:
V = -d(BA)/dt or -BA/t
If the magnetic field is increased by a factor of 4, (
) and the time required for the rod to move is decreased by a factor of 2 (
), the induced EMF becomes:


The EMF has increased by a factor of 8.