Question

explain what causes the object to travel fast on a curvilinear path? what other factors may effect the speed of the car ?

Answer 1

centripetal force acts on the body and  the car gains speed and moves faster. 
factors that effect the speed are:
1) mass
2) acceleration due to gravity

Answer 2

Centripetal force is the reason behind the object to travel fast on a curvilinear path.

Centripetal force is always directed towards centre.

Factors affecting The speed of the car:
--> mass 

if mass of the object increases then greater centripetal force is required to move faster.

---> Radius

A circle with smaller radius has smaller circumference.so greater centripetal force is needed to move it faster.