Answer:
The net friction force is 8.01 N
Explanation:
Net friction force = mass of hockey puck × acceleration
From the equations of motion
v^2 = u^2 + 2as
v = 40 m/s
u = 0 m/s (puck was initially at rest)
s = 30 m
40^2 = 0^2 + 2×a×30
60a = 1600
a = 1600/60 = 26.7 m/s^2
The acceleration of the puck is 26.7 m/s^2
Net friction force = 0.3 × 26.7 = 8.01 N
Answer
D.Diffraction
Explanation
Diffraction is a property that is experienced by waves when they come across a barrier when they are in motion.
The ways tends to curve behind the barrier. This is called diffraction of waves.
Now, sound is a wave and it also experience diffraction. . So the brother will be able to hear the sound due to diffraction
Answer:
Part a)

Part b)

Explanation:
Part a)
As we know that both charge particles will exert equal and opposite force on each other
so here the force on both the charges will be equal in magnitude
so we will have

here we have

now we have

Part b)
Now for the force between two charges we can say

now we have

now we have

Let's choose the "east" direction as positive x-direction. The new velocity of the jet is the vector sum of two velocities: the initial velocity of the jet, which is
along the x-direction
in a direction
north of east.
To find the resultant, we must resolve both vectors on the x- and y- axis:




So, the components of the resultant velocity in the two directions are


So the new speed of the aircraft is:

Answer:
(1)
(2)
but
transition not allowed.
Explanation:
Atoms can be described by the quantum number n, spin quantum number S, angular momentum quantum number L, and total angular momentum quantum number J. Based on approximation Russel- Saunders electron coupling, the atomic term symbol can be written as
.
The conditions or selection rule to promoting the electron are discussed below:
(1) The total spin should not change that is
.
(2) The total angular momentum change should be,
but
transition not allowed.