can I get some help with these questions. im not sure on these ones

During the stage of internal combustion engine operation in which the piston rises and compresses the fuel in the combustion chamber,
a. both the intake and exhaust valves are open
b. the intake valve is open and the exhaust valve is closed
c. both the intake and exhaust valves are closed
d. the exhaust valve is open and the intake valve is closed

how much heat energy is required to raise the temperature of 5 kilograms of coal from 20*c to 220*c
a.1324718
b.4187000
c.6573
d.314

1 answer

If any valves were open, you could not compress the gas.

5 KG * specific heat of coal * 200
coal around 1.3 *10^3 J/kgK
5 * 1.3 *10^3 * 200 = 1,300,000
so a.
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