The speed of light is determined by the medium (material) through which the light is travelling. Light travels faster in a vacuum than it does in any other medium. Light changes speed as it passes from one medium to another. This is called refraction.
Answer:43.7 N
Explanation:
Given
Mass of tennis ball is =57 gm
velocity of ball=21 m/s
The player volleys the ball straight back at 25 m/s(i.e. in opposite of initial direction)
time of contact=0.06 s
We know change in momentum
initial momentum
final momentum
change in momentum


Now 2.622

Answer:
the correct answue are B, A, C, C, B
Explanation:
1) The electric field is requested, let's approximate the membrane by a parallel plate with surface charge density
E =
E =
E = 5.65 10⁵ N / C
the correct answer is B
2) A calcium ion has two positive charges, so the force applied by each side of the membrane (plate)
F = q E
F = 2 1.6 10⁻¹⁹ 5.65 10⁵
F = 1.8 10⁻¹³ N
the total force is the sum of the force of each membrane and the two forces go to the same side
F = total = 2 F
F_total = 3.6 10⁻¹³ N
the correct answer is A
3) the field and the electric potential are related
ΔV = - E s
ΔV = - 5.65 10⁵ 10 10⁻⁹
ΔV = - 5.65 10⁻³ V
the correct answer is C
4) In the exercise they indicate that the outer wall has a positive charge, therefore, as they indicate that we approximate the system to a capacitor, the inner wall must be negatively charged.
The electric field goes from the positive to the negative charge, which is why it goes from the outer wall to the inner wall
the correct answer is C
5) For this part we use conservation of energy
starting point. On the inside wall, brown
Em₀ = U = qV
final point. On the outside
Em_f = K
energy is conserved
Em₀ = Em_f
q V = K
K = 3 10⁻¹⁵ 5.65 10⁻³
K = 1.7 10⁻¹⁷ J
the correct answer is B
The first living being to make an orbital spaceflight around the Earth was the dog Laika, aboard the Soviet spacecraft Sputnik 2 on 3 November 1957.
Answer:
b)
Explanation:
Normal force, is always directed upward the surface over which is placed the object, and can adopt any value, as required to meet Newton's 2nd Law.
In this case, as the external force on the suitcase pulls upward, in order to counteract the influence of gravity, normal force is less than the weight of the suitcase, as follows:
F + Fn = m*g
⇒ Fn = m*g - F
So, the normal force is equal to the magnitude of the weight of the suitcase (m*g) minus the magnitude of the force of the pull (F) which is the same expressed by the statement b.