John ( body mass= 65 kg) is taking off for a long jump . horizontal accerleration ax is 5m/s^2 and vertical acceleration ay is 0.9 m/s^2. a) calculate the horizontal ground reaction force f g, x .
b) calculate the vertical ground reaction force fg, y.
c) calculate the resultant ground reaction force fg?

(a) The horizontal ground reaction force  

(b)  The vertical ground reaction force

(c)   The resultant ground reaction force

Explanation:  

Given

John mass , m = 65 kg

Horizontal acceleration ,

Vertical acceleration ,

(a) Using Newton's 2nd law in horizontal direction

=>

Thus the horizontal ground reaction force  

(b) Using Newton's 2nd law in vertical direction

=>

=>

Thus the vertical ground reaction force

(c)  Resultant ground reaction force is

=>

=>

Thus  the resultant ground reaction force