Um corpo de massa m desliza sobre um plano horizontal com
velocidade constante. Sabendo que existe uma força de atrito
cujo coeficiente de atrito é = 0,5 entre o corpo e o plano e
após ter percorrido uma distância de 20m, o trabalho da força
de atrito foi de W= –2000J. Considerando que g = 10m/s2
,
podemos afirmar que a massa m em quilogramas do corpo é de
a) 50
b) 200
c) 20
d) 25
e) 40

Hydroelectricity provides about 7 percent of the electricity generated in the united states. (a) explain how a hydroelectric power plant converts energy stored in water into electricity. (b) identify two factors that determine the amount of electricity that can be generated by an individual hydroelectricity power plant. (c) describe the two main types of land-based hydroelectric power plants. (d) describe two economic advantages and two environmental disadvantages of hydroelectricity.

Aforce is a vector quantity because it has both?

In an exothermic chemical reaction the energy gained by the surroundings must be the energy lost by the reaction