Answer:
r = 5.08 m
Explanation:
The electric force of attraction or repulsion is given by :

We need to find how far above the electron would the proton have to be if you wanted to hold up an electron against the force of gravity by the attraction of a fixed proton some distance above it.
So, the force from the proton is balanced by the mass of the electron.

r is distance

So, proton have to be at a distance of 5.08 meters above the electron.
Answer:
the string and metre rule
Explanation:
Answer:
Options A and B.
Explanation:
Gravitational acceleration, initial height, intial speed and time are required to determine final speed. The option D is incorrect, since speed varies in time. Option C is dimentionally wrong.
The correct strategy is calculating the initial height from option B. Later, substituting time in equation A to derive an expression of the final velocity in terms of position. Hence, the required equations are options A and B.
The question is missing a diagram of the ray reflection. I attached a diagram which comes from a similar question in the answer section. The full question should be as follows:
Two plane mirrors intersect at right angles. A laser beam strikes the first of them at a point d = 10.0cmfrom their point of intersection, as shown in the figure. For what angle of incidence at the first mirror will this ray strike the midpoint of the second mirror (which is s=29.0cm long) after reflecting from the first mirror?
Answer:
34.6°
Explanation:
To strike the midpoint of the second mirror, the ray light will have to travel half of the distance vertically
i.e. 29/2 = 14.5
We can solve this through trigonometry.
Let the angle between the ray and the vertical plane mirror is known as α
tan α = 10/14.5
α =
= 34.6°
The angle of incidence is the angle between the ray and the normal line of the mirror.
Let angle of incidence of first mirror be β
β = α = 34.6
Air resistance, also called drag, acts upon a falling body by slowing the body down to thr point where it stops accelerating, and it falls at a constant speed, known as the terminal volocity of a falling object. Air resistance depends on the cross sectional area of the object, which is why the effect of air resistance on a large flat surfaced object is much greater than on a small, streamlined object.