His average speed all the way is
(50 meters) / (5 sec) = 10 m/s .
But, if the acceleration is uniform all the way down, then
Average speed = (1/2) (start speed + end speed)
Start speed = 0.
So
Average speed = (1/2) (0 + end speed)
= (1/2) of end speed .
10 m/s = (1/2) of end speed
End speed (at the bottom) = 20 m/s .
Magnitude of acceleration = (change in speed) / (time for the change)
= (20 m/s) / (5 sec)
= 4 m/s² .
<span>1.) It is 6.00km from your home to the physics lab. As part of your physical fitness program, you could run that distance at 10.0km/hr (which uses up energy at the rate of 700W ), or you could walk it leisurely at 3.00km/hr (which uses energy at 290 W).
A.)Which choice would burn up more energy?
running or walking?
b.)How much energy (in joules) would it burn?
c.)Why is it that the more intense exercise actually burns up less energy than the less intense one?
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billrussell42
Best Answer: running, at 10 km/hour for 6 km is
6 km / 10 km/hour = 0.6 hour or 36 min
energy used is 700 watts or 700 joules/s x 36 min x 60s/min = 1.512e6 joules or 1.5 MJ
walking, at 3 km/hour for 6 km
6 km / 3 km/hour = 2 hour or 120 min
energy used is 290 watts or 290 joules/s x 120 min x 60s/min = 1.872e6 joules or 1.8 MJ
C) should be obvious
PS, this has nothing to do with potential energy.
billrussell42 · 5 years ago
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Simon van Dijk
I assume the watt consumption is per hour. Then running 6km at 10.0 km/h results in 700*6/10 = 420 w.h and walking in 290*6/3 = 580 w.h So walking would burn up more energy (kwh)
b) 1 kilowatt hour = 3 600 000 joules
so 420 wh = 0.42 kwh = 1.51.10^6 joule
c) when you put more effort in making the distance your energy is used more efficient.
Simon van Dijk · 5 years ago
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B. A book sitting on a shelf. The books force is going down while the shelf's force is moving up against the book at an equal force.The answer would be B.
Answer:
Explanation:
During a car collision momentum of vehicle ceases within a fraction of seconds so Force due to the impulse is huge.
Impulse is defined as the product of average force and time. If we can increase the period of collision for the same impulse then the average force imparted will be less.
If we can increase the time period then damage due to collision will be less.
