Answer:
A. friction is greatly reduced.
Explanation:
Maglev train runs on the principle of repulsion force due to magnetic field
here we know that magnetic field will apply force on the train which helps to levitate train in air
This is why it runs forward due to other component of magnetic force and hence it can run with high speed in air with least friction as there is no two surfaces in contact with each other
So here we can say that
Train run with very high speed due to least value of friction between two surfaces which moves relative to each other
so correct answer is
A. friction is greatly reduced.
Answer:
a) The perimeter of the rectangle is 29.4 centimeters.
b) The uncertainty in its perimeter is 0.8 centimeters.
Explanation:
a) From Geometry we remember that the perimeter of the rectangle (
), measured in centimeters, is represented by the following formula:
(1)
Where:
- Width, measured in centimeters.
- Length, measured in centimeters.
If we know that 
and 
, then the perimeter of the rectangle is:
The perimeter of the rectangle is 29.4 centimeters.
b) The uncertainty of the perimeter (
), measured in centimeters, is estimated by differences. That is:
(2)
Where:
- Uncertainty in width, measured in centimeters.
- Uncertainty in length, measured in centimeters.
If we know that 
and 
, then the uncertainty in perimeter is:
The uncertainty in its perimeter is 0.8 centimeters.
Answer:
D they both are the same acceleration because they are in free fall
Answer: C
Explanation:
In collision, whether elastic or inelastic collisions, momentum is always conserved. That is, the momentum before collision will be equal to the momentum after collision.
Change in momentum of the system will be momentum after collision minus total momentum before collision.
Since momentum is a vector quantity, the direction will also be considered.
Momentum = MV - mU
Let
M = 800 kg is going north
at V = 20 m/s and the other car
m= 800 kg is going south
at U = 10m/s.
Substitute all the parameters into the formula
Momentum = (800 × 20) - (800 × 10)
= 8000 kgm/s
The final momentum after collision will also be equal to 8000 kgm/s
Change in momentum = 8000 - 8000
Change in momentum = 0
When material stuff is free to move, it moves away from stronger force on it to weaker force on it. OK ? Now take it to the next step: When material stuff is free to flow ... like liquid or gas ... it flows from higher pressure to lower pressure. That's what makes wind, and that's why water comes out of a garden hose when you open the nozzle. It doesn't amaze you at all when you INCREASE the pressure at one end of the straw (blow into it), and air moves DOWN and out of it. So it shouldn't bother you that when you DECREASE the pressure at your end, anything that's free to flow UP the straw will do that.
