Answer:
b) It is impossible to tell without knowing the masses.
Explanation:
The temperature change of a substance when it receives/gives off a certain amount of heat Q is given by
where
Q is the amount of heat
m is the mass of the substance
Cs is the specific heat capacity of the substance
In this case, we have a hot piece of aluminum in contact with a cold piece of copper: the amount of heat given off by the aluminum is equal to the amount of heat absorbed by the copper, so Q is the same for the two substances. However, we see that the temperature change of the two substances depends on two other factors: the mass, m, and the specific heat, Cs. So, since we know only the specific heat of the two substances, but not their mass, we can't tell which object will experience the greater temperature change.
Q=cm x change in t
Q= (390 J/kg C) x (0.045 kg) x (40.0 C)
Q= 702 J
Answer:
8.79 J
Explanation:
Given that a slinky is traveling down the stairs, like in the video clip below. What is the total KINETIC ENERGY of the slinky at the bottom of the stairs (just before it stops moving) IF the Height of the stairs is 2 meters, the weight of the slinky is 4.41 Newtons, its spring constant is 0.84 N/m, and the distance the slinky is initially stretched (to get it going) is 0.25 meters??
Total energy = mgh
Total energy = 4.41 × 2 = 8.82 J
Elastic potential energy = 1/2 × Ke^2
Elastic potential energy = 1/2 × 0.84 × 0.25^2
Elastic potential energy = 0.02625
Also,
Total energy = P.E + K.E
Substitute them into the formula above
8.82 = 0.02625 + K.E
K.E = 8.82 - 0.02625
K.E = 8.79375
K.E = 8.79 J
Therefore, the KINETIC ENERGY of the slinky at the bottom of the stairs is 8.79 Joules approximately
A force exerted by a person or object is energy or work.