If a spring constant is 60 n/m and an object hanging from it stretches it to 0.50 m, what is the mass of that object?

Since the spring is in vertical position, we determine the force it exerts to the spring by multiplying the spring constant with the length that the spring stretches. That is,
                                    force = (60 N/m)(0.50 m)
                                              = 30 N
Then, we divide the calculated force by the acceleration due to gravity, 9.8 m/s², giving us the answer of 3.06 kg.

Hence, the mass of the object is approximately 3.06 kg. 

The reflection of the candle in the concave mirror formed an upside-down virtual image that is smaller than the candle.in other words. the answer is the third option, c

The rocks expand when there hot/warm  and contract when they are cold.