Sure. The acceleration may be decreasing, but as long as it stays
in the same direction as the velocity, the velocity increases.
I think you meant to ask whether the body can have increasing velocity
with negative acceleration. That answer isn't simple either.
If the body's velocity is in the positive direction, then positive acceleration
means speeding up, and negative acceleration means slowing down.
BUT ... If the body's velocity is in the negative direction, then positive
acceleration means slowing down, and negative acceleration means
speeding up.
I know that's confusing.
-- Take a piece of scratch paper, write a 'plus' sign at one edge and
a 'minus' sign at the other edge. Those are the definitions of which
direction is positive and which direction is negative.
-- Then sketch some cars ... one traveling in the positive direction, and
one driving in the negative direction. Those are the directions of the
velocities.
-- Now, one car at a time:
. . . . . first push on the back of the car, in the direction it's moving;.
. . . . . then push on the front of the car, against its motion.
Each push causes the car to accelerate in the direction of the push.
When you see it on paper, all the positive and negative velocities
and accelerations will come clear for you.
The power is defined as the work done (W) by the transmission per unit of time (t) to accelerate the train:
To find the work done, we can use the work-energy theorem, which states that the work done is equal to the variation of kinetic energy of the train. Since the trains starts from rest, its initial kinetic energy is zero, so the work done is simply equal to the final kinetic energy:
where m is the mass of the train and
is its final velocity.
The mass of the train is m=0.875 kg while its final velocity is
, the work done by the electrical transmission is
And since this work is done in a time of t=20.5 ms=0.0205 s, the minimum power delivered is
1450.4 newtons has to be applied so the object can move , because At average gravity on Earth (conventionally,g = 9.80665 m/s2), a kilogram mass exerts a force of about 9.8 newtons. An average-sized apple exerts about one newton of force, which we measure as the apple's weight.
Electromagnetic waves<span> are made of oscillating magnetic and electric fields, and like all </span>waves<span>, they carry energy</span>
Answer:
B
Explanation:
to see how fast she is going per second, you would have to divide the distance traveled by the seconds it took to travel the distance