I would say a because i just had this
K.e=1/2mv²
K.e=1/2 2(5)²
K.e=1/2 2×25
K.e=50/2
K.e=25J
(b) 71%
The thermal efficiency of a Carnot heat engine is given by:
where
W is the useful work done by the engine
is the heat in input to the machine
In this problem, we have:
is the heat absorbed
is the work done (175 kJ is the heat released to the sink, therefore the work done is equal to the difference between the heat in input and the heat released)
So, the efficiency is
(a) 
The efficiency of an engine can also be rewritten as
where
is the absolute temperature of the cold sink
is the temperature of the source
In this problem, the temperature of the sink is
So we can re-arrange the equation to find the temperature of the source:
Electrical force is the repulsive or attractive force of attraction between any two charged bodies. it is possible to calculate electric force on anything that runs on batteries or uses a plug. Its net effect can be explained using newtons law of motion like any force.
From the coulombs law; F = k (q1║q2)/ r²
Where k = 9 ×10∧9 N.m².C∧-2, r12= 0.285m, q2= +6μC and q1 = 4.86 nC
substituting values in the equation
the net electrical force acting on the +6ц C charge is 5.4 N.
i think its D, all of them.
