Answer:
(B) The total internal energy of the helium is 4888.6 Joules
(C) The total work done by the helium is 2959.25 Joules
(D) The final volume of the helium is 0.066 cubic meter
Explanation:
(B) ∆U = P(V2 - V1)
From ideal gas equation, PV = nRT
T1 = 21°C = 294K, V1 = 0.033m^3, n = 2moles, V2 = 2× 0.033=0.066m^3
P = nRT ÷ V = (2×8.314×294) ÷ 0.033 = 148140.4 Pascal
∆U = 148140.4(0.066 - 0.033) = 4888.6 Joules
(C) P2 = P1(V1÷V2)^1.4 =148140.4(0.033÷0.066)^1.4= 148140.4×0.379=56134.7 Pascal
Assuming a closed system
(C) Wc = (P1V1 - P2V2) ÷ 0.4 = (148140.4×0.033 - 56134.7×0.066) ÷ 0.4 = (4888.6 - 3704.9) ÷ 0.4 = 1183.7 ÷ 0.4 = 2959.25 Joules
(C) Final volume = 2×initial volume = 2×0.033= 0.066 cubic meter
Answer:
In terms of distance, average speed is 20 km/h
In terms of displacement, average speed is 0 km/h.
Explanation:
Total distance:

Total time is 3.0 hours
but:

In terms of distance.
substitute:


In terms of displacement:

Answer:
a). A conservative force permits a two-way conversion between kinetic and potential energies.
TRUE
Because there is no energy loss in presence of conservative forces so energy conversion in two ways are possible.
b). A potential energy function can be specified for a conservative force.
TRUE
negative gradient of potential energy is equal to conservative force

c). A non-conservative force permits a two-way conversion between kinetic and potential energies.
FALSE
here energy is lost against non-conservative forces
d). The work done by a conservative force depends on the path taken.
FALSE
work done by conservative force is independent of path
e). The work done by a non-conservative force depends on the path taken.
TRUE
work done by non conservative forces depends on path.
f). A potential energy function can be specified for a non-conservative force.
FALSE
It is not defined for non conservative forces
Answer:
a) 0.31 rad/s
b) 100 J
c) 6.67 W
Explanation:
(a) the force would generate a torque of:

According to Newton 2nd law, the angular acceleration would be

It starts from rest, then after 15s it would achieve a speed of

(b) The distance angle swept by it is:

Hence the work by the child

c) Average power to work per time unit

Its rays point away from the charge