Which statement best describes a risk associated with using radioisotopes in nuclear reactors? A Radioisotopes are very expensiv
1 answer:
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Answer:
Explanation:
When a projectile is fired upwards with some initial speed then the it reaches the top of the projectile and then falls back to the ground.
According to the question we need to find the work done by the gravity which is acting downwards for the projectile when it is at a position just about to hit the ground in course of falling down.
As we know that work is given as:
here:
force of gravity on the object (which is acting downwards)
displacement of the object
- Here the work done by the gravity at an instant just before the projectile hits the earth will be negative as the displacement is in the direction opposite to the force of gravity.
Answer:
K' = 1200 J
Explanation:
To find the kinetic energy you first take into account the formula for the kinetic energy of the charge:
= 800J (1)
m: mass of the charge
v: final speed of the charge when it reaches the positively charged plate.
Furthermore, you have that the acceleration of the charge is obtained by using the second Newton law:
(2)
a: acceleration
E: electric field
q: charge
The electric field between two parallel plates is V/d, being V the potential difference and d the separation between plates. You replace E in (2) and obtain:
Next, you take into account the following formula for the calculation of the final speed of the charge:
Next, you replace this value of v in (1):
= 880J (3)
If the distance between plates is tripled, and the potential difference is halved, you have for the new final speed:
And the kinetic energy becomes:
(4)
You calculate the ratio between both kinetic energies K and K', that is, you divide equations (3) and (4), in order to find the new kinetic energy:
hence, the kinetic energy of the charge incresases to 1200J