Lol I just learned this, here's the short answer:
Large doses of X-Rays are known to cause cell damage and
cancer, so
<span>X-Ray technicians have to stand behind the shield. Here's the lengthy answer:
</span>
This is because the patient would only be exposed to the small
dose of radiation once, which is hardly harmful. However, radiographers
deal with this all day every day, which could mean that the small doses
could add up. This is why they stand behind a lead screen; the small
exposure to the X-Rays aren't harmful alone but frequent exposure could
begin to damage your cells and lead to potential genetic mutation. If a
patient is often in radiography (a long-stay patient for example), they
begin to wear lead aprons whilst being X-rayed in order to prevent the
risk of harm. Hope I answered correctly.
Given that,
Mass of a baseball, m = 0.2 kg
Initial speed of a baseball, u = 30 m/s
Force produced by a bat, F = 2000 N
Final speed of a baseball, v = -50 (negative for opposite direction)
To find,
For how long was the ball in contact with the bat?
Solution,
Let for t seconds the ball is in contact with the bat. The net force acting on the ball is given by :
So, the ball is contact with the bat for 8 ms.
I believe it is call “Acceleration”
Answer: option b.
Explanation:
The kinetic energy of a spring with constant K is calculated as:
kinetic energy = (k/2)*x^2
Where x^2 is the displacement of the spring with respect to it's rest position.
This can be written as a function like:
x = A*cos(2*pi*f*t)
where:
A is the amplitude (the maximum distance that the spring can move in each direction)
f is the frequency (and 2*pi*f is the angular frequency)
and t is the variable, it represents the time.
Replacing this in the kinetic energy equation, we get:
kinetic energy = (k/2)*(A*cos(2*pi*f*t))^2
This is the same as the option b: b. 1/2kA^2cos^2(2πft)
Then the corrrect option is b.
The answer to your question is, b.