I think to an observer outside the train, the speed of the ball will actually look like more than the speed of the train.
The old style (incandescent) light bulb converts more energy
into heat than it does into light. If you're using it mainly as a
source of light, then it's a bummer, and its efficiency is very low.
BUT ... if you're using an incandescent light bulb as a heater, then
its efficiency is much better. It all depends on your point of view.
Answer:
35.6 N
Explanation:
We can consider only the forces acting along the horizontal direction to solve the problem.
There are two forces acting along the horizontal direction:
- The horizontal component of the pushing force, which is given by
with 
- The frictional force, whose magnitude is
where 
, m=8.2 kg and g=9.8 m/s^2.
The two forces have opposite directions (because the frictional force is always opposite to the motion), and their resultant must be zero, because the suitcase is moving with constant velocity (which means acceleration equals zero, so according to Newton's second law: F=ma, the net force is zero). So we can write:
Answer:
6ms^-1
Explanation:
Given that the frequency difference is
( 563- 544) = 19
So alsoThe wavelength of each wave is = v/f = 344 /544
and there are 19 of this waves
So it is assumed that each motorcycle has moved 0.5 of this distance
in one second thus the speed of the motorcycles will be
=> 19/2 x 344/544 = 6.0 m/s
Answer:
D. Calculate the area under the graph.
Explanation:
The distance made during a particular period of time is calculated as (distance in m) = (velocity in m/s) * (time in s)
You can think of such a calculation as determining the area of a rectangle whose sides are velocity and time period. If you make the time period very very small, the rectangle will become a narrow "bar" - a bar with height determined by the average velocity during that corresponding short period of time. The area is, again, the distance made during that time. Now, you can cover the entire area under the curve using such narrow bars. Their areas adds up, approximately, to the total distance made over the entire span of motion. From this you can already see why the answer D is the correct one.
Going even further, one can make the rectangular bars arbitrarily narrow and cover the area under the curve with more and more of these. In fact, in the limit, this is something called a Riemann sum and leads to the definition of the Riemann integral. Using calculus, the area under a curve (hence the distance in this case) can be calculated precisely, under certain existence criteria.
