Answer:
The work required to stretch a spring 12 ft beyond its natural length is 432 ft-lb
Explanation:
The work to stretch a spring is calculated using the formula:
Equation (1)
W = work in ft-lb
k = spring constant in lb/ft
x = spring deformation in ft
we clear k from the equation (1)
Equation (2)
We replace x = 2ft, W = 12 ft-lb in the equation (2)
Calculation of work required to stretch spring 12 ft
We replace k = 6 lb/ft and x = 12ft in the equation (1)
Answer:
option (3)
Explanation:
According to the ideal gas equation
PV = nRT
where, P is pressure, V is volume, R is gas constant and T be the absolute temperature.
At constant volume,
P ∝ T
If the temperature is doubled, the pressure also doubled.
As volume is constant, so the density is also constant.
So, the pressure is doubled and the density remain constant.
Efficacy is the ratio of light output from a lamp or a bulb to the electric power it consumes and is measured in lumens per watt (LPW).
In this case; the power is 4 watt and the number of lumens is 240.
Efficacy = lumens/power
= 240/4
= 60 lm/W
Thus the efficacy of the bulb is 60 lm/W