Answer:
flux=13.92W/m^2
Explanation:
The heat transfer by conduction consists in the transport of energy through particles that are together, that is to say by means of solids, Newton developed an equation that allows to know the heat transported in a flat plate knowing the cross sectional area A, Thickness L, conductivity K and a temperature difference between the internal and external surface.
Q=KA(t2-t1)/L
To know the heat flux we simply divide both sides of the equation by the area.
Flux=K(t2-t1)/L
where
K=0.029w/mk
L=25mm=0.025m
t2-t1=12 ° C
solving
Flux=(0.029)(12)/(0.025)
flux=13.92W/m^2
<span>When a person lifts the block, the block has more potential energy. Therefore the person does positive work on the block.
work = m g h
work = (4.5 kg) (9.80 m/s^2) (1.2 m)
work = 52.92 joules
The person's work on the block is 52.92 joules
When the block is being raised, the force of gravity opposes the motion. Therefore the force of gravity does negative work on the block.
work = - (force) (h)
work = - m g h
work = -(4.5 kg) (9.80 m/s^2) (1.2 m)
work = -52.92 joules
The work done by the force of gravity on the block is -52.92 joules
Note that when the block is moved horizontally, the potential energy does not change. Therefore there is no work done on the block when it moves horizontally (we are assuming that the kinetic energy does not change).</span>
Answer: D.
Explanation: Just took the quiz.
Answer:
37.5 N Hard
Explanation:
Hook's law: The force applied to an elastic material is directly proportional to the extension provided the elastic limit of the material is not exceeded.
Using the expression for hook's law,
F = ke.............. Equation 1
F = Force of the athlete, k = force constant of the spring, e = extension/compression of the spring.
Given: k = 750 N/m, e = 5.0 cm = 0.05 m
Substitute into equation 1
F = 750(0.05)
F = 37.5 N
Hence the athlete is pushing 37.5 N hard
