Since force is mass*acceleration,
F = 70kg * 9.8 m/s
 
        
             
        
        
        
A force is a push or pull acting upon an object as a result of its interaction with another object. There are a variety of types of forces. a variety of force types were placed into two broad category headings on the basis of whether the force resulted from the contact or non-contact of the two interacting objects.
Contact Forces
Action-at-a-Distance Forces
Frictional Force
Gravitational Force
Tensional Force
Electrical Force
Normal Force
Magnetic Force
Air Resistance Force
Applied Force
Spring Force
These are types of individual forces
Applied Force
Gravitational Force
Normal Force
Frictional Force
Air Resistance Force
Tensional Force
Spring Force
        
             
        
        
        
Answer:
You're right already. It's B)
 
        
                    
             
        
        
        
We can solve the problem by applying Newton's second law, which states that the resultant of the forces acting on an object is equal to the product between its mass and its acceleration:

We should consider two different directions: the direction perpendicular to the inclined plane and the direction parallel to it. Let's write the equations of the forces along the two directions, decomposing the weight of the object (mg):

 (parallel direction) (1)

 (perpendicular direction) (2)
where

 is the angle of the inclined plane, N is the normal reaction of the plane, 

 is the frictional force, with 

 being the coefficient of friction.
From eq.(2), we find

and if we substitute into eq.(1), we can find the acceleration of the block:

from which
