To get the solution you must need to draw a force triangle. Attach the head of the 60N north force arrow with the tail of the 60N east force arrow. The subsequent is the arrow connecting he tail and head of the two arrows.
You get a right angled triangle, and the resultant is (60^2 + 60^2) ^0.5 = 84.85 N or 85 N northeast.
Answer:
Reflective
Explanation:
The radiation pressure of the wave that totally absorbed is given by;

and While the radiation pressure of the wave totally reflected is given by;

Now compare the two-equation you can clearly see that the pressure due to reflection is larger than absorption therefore the sail should be reflective.
Answer:
0.25m²
Explanation:
We know that the summation of forces in the vertical direction is zero
So
PA-mg=0
A=mg/p
So
Substituting
A= 75* 9.8/3*10^-3
=0.25m² which is the total shoe area
Answer:
(C) Only if it starts moving
Explanation:
We know that work done is given by

So there are two case in which work done is zero
First case is that when force and displacement are perpendicular to each other
And other case is that when there is no displacement
So for work to be done there must have displacement, if there is no displacement then there is no work done
So option (c) will be the correct option
Explanation:
Given that,
Wavelength of the light, 
Work function of sodium, 
The kinetic energy of the ejected electron in terms of work function is given by :

The formula of kinetic energy is given by :

Hence, this is the required solution.