B because radio waves make a sound that are short
Answer:
The object will have an upward acceleration
Explanation:
Let's consider the forces applied on the box. We have only two forces:
- The applied force of push,
, downward
- The force of gravity,
, (also known as weight of the object), downward
Therefore, the net force on the box is:

Here, we know that force applied is equal or greater than the weight, so

And therefore the net force is greater than zero:
(1)
According to Newton's second law of motion, the net force on the box is equal to the product between its mass and its acceleration:

where
m is the mass of the box
a is its acceleration
Given (1), this means that

Therefore, the box will have an upward acceleration.
In this case force example we have:

So the mass of the box is

So the net force is

And the acceleration is

Answer:
The period would decrease by sqrt(2)
Explanation:
The restoring force is given by,
F = -kx
According to Newton's second law of motion,
ma = -kx
ma + kx = 0
The time period is given by,
T =
Where
is the angular velocity and it is given by,
= 
Now if the spring constant is doubled then,

Thus,
=



Thus, The period would decrease by sqrt(2).
Hence, option D is correct.
Answer:

Explanation:
For light passing through a single slit, the position of the nth-minimum from the central bright fringe in the diffraction pattern is given by

where
is the wavelength
D is the distance of the screen from the slit
d is the width of the slit
In this problem, we have
is the wavelength of the red light
D = 14 m is the distance of the screen from the doorway
d = 1.0 m is the width of the doorway
Substituting n=1 into the equation, we find the distance between the central bright fringe and the first-order dark fringe (the first minimum):
