Answer:
(A) We are using them faster than they are replenished by nature
Its resistor :}...............
Answer:
velocity during second d = 20.0 mi/h
Explanation:
Total distance travelled is 2d, with an average velocity of 30.0 mi/h you can express the time travelled in terms of d:
distance = velocity * time
time = distance / velocity
time = 2d/30.0
The time needed for the first d at 60.0 is:
time = d/60.0
The time in the second d you can get it by substracting both times (total time - time for the first d)
second d time = 2d/30.0 - d/60.0
= 4d/60.0 - d/60.0
= 3d/60.0
and with the time (3d/60.0) and the distance travelled (d) you can get the velocity:
velocity = distance / time
velocity = d / (3d/60.0)
= 60.0/3 = 20.0 mi/h
Answer:
Explanation:
(b) The initial velocity is added to that due to acceleration by gravity. The velocity is increased linearly by gravity at the rate of 9.8 m/s². The average velocity of the pebble will be its velocity halfway through the 2-second time period.* That is, it will be ...
4 m/s + (9.8 m/s²)(2 s)/2 = 13.8 m/s . . . . average velocity
__
(a) The distance covered in 2 seconds at an average velocity of 13.8 m/s is ...
d = vt
d = (13.8 m/s)(2 s) = 27.6 m
The water is about 27.6 m below ground.
_____
* We have chosen to make use of the fact that the velocity curve is linear, so the average velocity is half the sum of initial and final velocities:
vAvg = (vInit + vFinal)/2 = (vInit + (vInit +at))/2 = vInit +at/2
__
If you work this in a straightforward way, you would find distance as the integral of velocity, then find average velocity from the distance and time.
