With acceleration
and initial velocity
the velocity at time <em>t</em> (b) is given by
We can get the position at time <em>t</em> (a) by integrating the velocity:
The particle starts at the origin, so .
Get the coordinates at <em>t</em> = 8.00 s by evaluating at this time:
so the particle is located at (<em>x</em>, <em>y</em>) = (64.0, 64.0).
Get the speed at <em>t</em> = 8.00 s by evaluating at the same time:
This is the <em>velocity</em> at <em>t</em> = 8.00 s. Get the <em>speed</em> by computing the magnitude of this vector:
<span>E=hc/wav. len
E = (6.62 x 10^-34 x 3 x 10^8)/0.0275 x 10^-9
E = 7.22182 x 10^-15 J
To convert to eV divide by 1.6 x 10^-19
E = 7.22182 x 10^-15/1.6 x 10^-19 eV
E =45.36 x 10^3 eV
Th energy, E, of a single x-ray photon in eV is = 45.36keV.
Number of photons, n = total energy/ energy of photon
n = 3.85 x 10^-6/7.22182 x 10^-15
n = 5.33 x 10^8 photons </span>
Answer:
A 3 feet radius snowball will melt in 54 hours.
Explanation:
As we can assume that the rate of snowball takes to melt is proportional to the surface area, then the rate for a 3 feet radius will be:
T= A(3 ft)/A(1 ft) * 6 hr
A is the area of the snowballs. For a spherical geometry is computing as:
A=4.pi.R^2
Then dividing the areas:
A(3 feet)/A(1 foot) = (4 pi (3 ft)^2)/(4 pi (1 ft)^2) = (36pi ft^2)/(4pi ft^2)= 9
Finally, the rate for the 3 feet radius snowball is:
T= 9 * 6 hr = 54 hr
Answer:
The statement is true: velocity and acceleration have opposite directions in the interval of braking.
Explanation:
Let's say we have a velocity .
The acceleration is the rate of change of the velocity . This means that if is <em>increasing during</em> time, then must be positive. But if is <em>decreasing over</em> time, then will be negative (even though the velocity is positive).
Mathematically:
decreases ⇒
⇒.
Example:
Answer:
Q = - 256 X 10⁻⁷ C .
Explanation:
Electric field due to a charge Q at a distance d from the center is given by the expression
E = k Q /d² Where k is a constant and it is equal to 9 x 10⁹
Put the given value in the equation
9 x 10² =
Q =
Q = - 256 X 10⁻⁷ C .
It will be negative in nature as the field is directed towards the center.