The heat released or absorbed by a process where temperature changes is calculated from the product of the mass of the sample, its heat capacity (4.18 J/g C for water) and the change of the temperature.

Heat = mC(T)
Heat = 90 (4.8) (64) = 27648 J or 27.65 kJ needed

8 0

4 years ago

An elevator is moving down with an acceleration of 3.36 m/s2.

sergeinik [125]

Answer : 413.44N

Here it is given that an elevator is moving down with an acceleration of 3.36 m/s² . And we are interested in finding out the apparent weight of a 64.2 kg man . For the diagram refer to the attachment .

From the elevator's frame ( non inertial frame of reference) , we would have to think of a pseudo force.
The direction of this force is opposite to the direction of acceleration the frame and its magnitude is equal to the product of mass of the concerned body with the acceleration of the frame .
When a elevator accelerates down , the weight recorded is less than the actual weight .

From the Free body diagram ,

$\sf\longrightarrow Weight = mg - ma \\$