A judgement or an observation?
Answer:
Approximately
(downwards.)
Assumptions:
- the rocket started from rest;
- the gravitational acceleration is constantly
; - there's no air resistance on the rocket and the two fragments.
- Both fragments traveled without horizontal velocity.
Explanation:
The upward speed of the rocket increases by
. If the rocket started from rest, the vertical speed of the rocket should be equal to
.
The mass of the rocket (before it exploded) is 1500 kilograms. At 20 m/s, its momentum will be equal to
.
What's the initial upward velocity,
, of the lighter fragment?
The upward velocity of the lighter fragment is equal to
once it reached its maximum height of
.
.
.
Mass of the two fragments:
- Lighter fragments:
. - Heavier fragment:
.
Initial momentum of the lighter fragment:
.
If there's no air resistance, momentum shall conserve. The momentum of the lighter fragment, plus that of the heavier fragment, should be equal to that of the rocket before it exploded.
The initial momentum of the heavier fragment should thus be equal to the momentum of the two pieces, combined, minus the initial momentum of the lighter fragment.
.
Velocity of the heavier fragment:
.
Answer:
3m
Explanation:
p=250w
m=25.5
t=3.0s
D=x
F=mxa F= 25.5kg x 9.8m/s^2 =250N
D= 250wx3.0s/250w
3m
B. Some of the ball’s energy is transformed to thermal energy.
Hope this helps you!
Answer:
The slower the train is moving, the less are the changes of the magnetic flux, thus the eddy currents become weaker.
Explanation:
A magnetic brakes is not a very efficient way of braking when a train is moving slowly because at low speeds, the changes in the magnetic flux are very less and so it causes the eddy current to become weaker.
Let us find the drag force which is proportional to the velocity of two conducting plates.
The EMF that is induced in the eddy currents are : 
The force which is due to the induced magnetic field is, 
Therefore, 

Here, force is directly proportional to the velocity of the two conducting plates.
Therefore, we can say that when the speed of the train is low, the magnetic flux changes are less and thus the eddy currents are weaker.