Answer:

Explanation:
The period of a physical pendulum is:



The length of the leg is approximately the height of the person:

The period is:


(a) The skater covers a distance of S=50 m in a time of t=12.1 s, so its average speed is the ratio between the distance covered and the time taken:

(b) The initial speed of the skater is

while the final speed is

and the time taken to accelerate to this velocity is t=2 s, so the acceleration of the skater is given by

(c) The initial speed of the skater is

while the final speed is

since she comes to a stop. The distance covered is S=8 m, so we can use the following relationship to find the acceleration of the skater:

from which we find

where the negative sign means it is a deceleration.
Answer:
2677.3 N
Explanation:
v₀ = initial speed of the hand = 4.75 m/s
v = final speed of the hand = 0 m/s
m = Total mass of hand and forearm = 1.55 kg
t = time interval for hand to come to rest = 2.75 ms = 0.00275 s
F = Force applied on the leg
Using Impulse-change in momentum equation
F t = m (v - v₀)
F (0.00275) = (1.55) (0 - 4.75)
F = - 2677.3 N
magnitude of force = 2677.3 N
Answer:
No
Explanation:
The reason why no current is produced are basically that, the wavelengths of light in the Balmer transition are reflected, not absorbed in solar panels, hence no current is produced.
The Balmer series consists of lines in the visible spectrum. It corresponds to emission of a photon of light when electrons descend from higher energy levels to the n=2 level in the hydrogen spectrum. The various wavelengths in the Balmer series can be separated by a prism since they are all in the visible region of the electromagnetic spectrum.
In solar panels, light corresponding to the wavelengths in the Balmer series is merely reflected by the panel and not absorbed. Since light is not absorbed, no current can be produced when the panel is irradiated with light corresponding to the wavelengths in the Balmer series.
Answer:
On the magnitude of the charges, on their separation and on the sign of the charges
Explanation:
The magnitude of the electric force between two charges is given by

where
k is the Coulomb's constant
q1, q2 are the magnitudes of the two charges
r is the separation between the charges
From the formula, we see that the magnitude of the force depends on the following factors:
- magnitude of the two charges
- separation between the charges
Moreover, the direction of the force depends on the sign of the two charges. In fact:
- if the two charges have same sign, the force is repulsive
- if the two charges have opposite signs, the force is attractive