Answer:
Explanation:
Mass doesn't matter here because when something is falling, gravity plays fairly; an elephant falls at the same rate of acceleration as does a feather. What DOES matter is everything pertinent to the y-dimension of free-fall:
a = -9.8 m/s/s
v₀ = 0 (since the ball was held before it was dropped)
v = ??
Δx = -8 m (negative because the ball drops this far below the point from which it was released).
Putting all this together in one equation:
v² = v₀² + 2aΔx and filling in this equation:
v² = (0)² + 2(-9.8)(-8) and
v² = 156.8 so
v = 12.5 which rounds to 13 if you're using 2 sig figs, and rounds to 10 if you're only using 1 (which you should be, according to the way the numbers have been given in this problem)
Answer:
Waves of energy traveling through a space
Explanation:
Answer:
Work Done= 3150J
Power= 1.75W
Explanation:
Work Done= Force x the distance travelled in the direction of the force (W= f x d)
Weight is a force, i think the qn. stated it wrongly, it should be 70N not 70kg.
Work Done= 70 x 45
=3150J
Power= Work Done/Time
=3150/(30x60)
*convert minutes to seconds since the S.I. unit of Power is joules/seconds(J/s) or watts(W)
=1.75W
Distance = (speed) x (time)
Distance = (3 x 10⁸ meter/second) x (1 hour)
Distance = 3 x 10⁸ meter-hour per second
Distance = 3 x 10⁵ kilometer-hour per second
Hmmm. That answer is perfectly correct and totally useless. We have no idea how far one meter-hour per second is. It's a unit we never use. We'd better convert the answer to a unit of length that we use every day.
(3 x 10⁵ km-hour/sec) x (3,600 sec/hour) =
(3 x 10⁵ x 3,600) (km-hour-sec/hour-sec) =
1.08 x 10⁹ km
THAT's it ! A pulse of light in vacuum travels 1.08 billion km in one hour.
The answer is C. <span>animals digging rocks</span>
