Some workers do 15000 J of work on a 3500 N crate to push it up a ramp. The ramp is 4 m high. What is the efficiency of the ramp?

93.3%

Explanation:

Efficiency of ramp is given by

Where n is the efficiency, W is work and subscripts o and i represent output and input respectively.

The work input is what the workers do and that is given as 15 kJ

The work output

Since work is product of force and perpendicular distance and substituting force with 3500 N and distance with 4 m we get that the work output is 3500*4=14000 J= 14 kJ

Finally, substituting 14 kJ and 15 kJ for work output and input respectively we deduce that

do you have a formula possibly

electric field is a function of 1/r^2

yes, the force per unit charge for a point charge is inverse square law.