1) It is because they produce a lot of pollution in the atmosphere
2) They are limited in number and can't be recycled
Hope this helps!
Answer:
-48 N
Explanation:
mass of door (m) = 4 kg
acceleration of the door = 12 m/s^{2}
force exerted by the person = 48 N
From Newton's third law of motion, action and reaction are equal but opposite. Therefore the force exerted on the door by the person which is 48 N will be the same as the force exerted on the person by the door but opposite in its direction, and this would be - 48 N
The elastic potential energy of a spring is given by

where k is the spring's constant and x is the displacement with respect to the relaxed position of the spring.
The work done by the spring is the negative of the potential energy difference between the final and initial condition of the spring:

In our problem, initially the spring is uncompressed, so

. Therefore, the work done by the spring when it is compressed until

is

And this value is actually negative, because the box is responsible for the spring's compression, so the work is done by the box.
Answer:

Explanation:
From the question we are told that
Weight 
Altitude 
Speed 
Generally the equation for Potential energy ids mathematically given as




Answer:
The number of bright fringes per unit width on the screen is,
Explanation:
If d is the separation between slits, D is the distance between the slit and the screen and
is the wavelength of the light. Let x is the number of bright fringes per unit width on the screen is given by :

is the wavelength
n is the order
If n = 1,

So, the the number of bright fringes per unit width on the screen is
. Hence, the correct option is (B).