Answer:
ΔU = -70 J
Explanation:
ΔU = Q − W
where ΔU is the change in internal energy,
Q is the heat absorbed by the system,
and W is the work done by the system (on the surroundings).
30 J of thermal energy is released, so Q = -30 J.
40 J of work is done by the system, so W = 40 J.
Therefore, the change in internal energy is:
ΔU = -30 J − 40 J
ΔU = -70 J
Answer:
The small pebble
Explanation:
Since the potential energy, P.E lost equals kinetic energy, K.E gained,
P.E = K.E
P.E = mgh = K.E
So, K.E = mgh where g = acceleration due to gravity and h = height of drop
Since h and g are constant
K.E ∝ m
So, the kinetic energy of the object is directly proportional to its mass. Thus, the object with the smaller mass has the lesser kinetic energy.
Since the object with the smaller mass is the small pebble, so the small pebble would have less kinetic energy as it crashes on the road at the bottom of the mountain.
Part A:
To answer this item, we need to convert the given revolutions per minute in speed expressed as miles per hour. In order to do so, we need to use the dimensional analysis and the appropriate conversion factor.
We calculate the circumference that is covered by the wheel.
C = πD
where C is the circumference and D is the diameter.
Substitute the known values,
C = π(26 in) = 81.68 inches
The speed tested is calculated below.
s = (81.68 inches/rev)(480 rev/min)(1 mil/63360 inches)(60 min/1 hr)
s = 37.127 mil/h
<em>ANSWER: 37.127 mil/h</em>
Part B:
Similar to what was done in Part A, the setting of the balancer is calculated below,
setting = (80 mil/h)(1h/60 min)(63360 in/1 mil)(1 rev/81.68 in)
setting = 1034.23 rev/min
<em>ANSWER: 1034.23 rev/min</em>
Answer:
k = 652 lb/ft
Explanation:
Given :
Weight of the collar = 1.6 lb
The upstretched length of the spring = 6 in
Speed = 16 ft/s
PA = 8 + 10
= 18 inch
Let the initial elongation be 
∴ = 18 - 6
= 12 inch = 1 foot
= 13.925 inch
Final elongation in the spring
inch = 0.66 feet
Applying the conservation of the mechanical energy between A and B is
![$\frac{1}{2}k[(1)^2-(0.66)^2]=\frac{1.6}{2}\times (16)^2-1.6 \times 32 \times \frac{5}{12}$](https://tex.z-dn.net/?f=%24%5Cfrac%7B1%7D%7B2%7Dk%5B%281%29%5E2-%280.66%29%5E2%5D%3D%5Cfrac%7B1.6%7D%7B2%7D%5Ctimes%20%2816%29%5E2-1.6%20%5Ctimes%2032%20%5Ctimes%20%5Cfrac%7B5%7D%7B12%7D%24)
k = 652 lb/ft
