Answer:
F'= 4F/9
Explanation:
Two small objects each with a net charge of +Q exert a force of magnitude F on each other. If r is the distance between them, then the force is given by :
...(1)
Now, if one of the objects with another whose net charge is + 4Q is replaced and also the distance between +Q and +4Q charges is increased 3 times as far apart as they were. New force is given by :
.....(2)
Dividing equation (1) and (2), we get :

Hence, the correct option is (d) i.e. " 4F/9"
Find the force that would be required in the absence of friction first, then calculate the force of friction and add them together. This is done because the friction force is going to have to be compensated for. We will need that much more force than we otherwise would to achieve the desired acceleration:

The friction force will be given by the normal force times the coefficient of friction. Here the normal force is just its weight, mg

Now the total force required is:
0.0702N+0.803N=0.873N
Answer:
E = hv
Explanation:
- The photoelectric effect is a phenomenon when the electromagnetic waves of a particular wavelength strike on the metal plate like zinc, it ejects the free electrons.
- The ejected electrons have the kinetic energy and this energy is responsible for the electric energy.
- The kinetic energy of the emitted electrons is linked with the frequency of the incident rays.
- If the rays hitting the metal plate is below the minimum required threshold value, the photoelectrons are not ejected.
- The photoelectric equation is given by
E = hν - ∅
Where, ∅ is the minimum energy required to remove an electron.
I'm not too sure but I think it's nuclear decay
D. Power. The unit of power is watt.