Which energy changes take place when a pedalling cyclist uses a generator (dynamo) to light his bicycle lamp?

chemical → kinetic → electrical → light

Explanation: At the same time when the generator lights up the bicycle lamp the lamp lights up using electrical energy so mechanical energy is also transformed into electrical energy.

if the person is shown to have +90n, then ans is -10n.

if the person is shown to have -90n, then ans is +10n.

see the picture for the vector

the magnitude of the vector by pythagorean theorem

r = √( (-10)^2 + (3)^2 ) = √109

magnitude = √109 units

the direction angle between vector and x-axis is

tan^(-1)(3/10) = 16.699

so the direction is approximately 16.7 degrees north of west