Answer:
The average velocity is 40km/h.
Explanation:
The average velocity is 
, where 
is the distance traveled and 
the time elapsed.
The distance traveled is clearly 80km since it's all done in the same direction, we only need to know the time elapsed. For this we calculate the time elapsed on the first part, and add it to the time elapsed on the second part using always the formula 
, where v is the velocity on each part, which is constant.
The time elapsed for the first part is 
, and the time elapsed for the second part is 
, giving us a total time of 
=2h.
Finally, we can calculate the average velocity: 
.
D. both b. and c. Obviously adding more gas but reducing the volume because of the limited space in the container.
As we know that work done is defined as product of force and displacement in the direction of applied force
so we can say it is
or we can say
so we will have following options
A)Pushing against a locked door
There is no work done in above case as there will be no displacement in that case so work done is ZERO
B) Carrying a box down a corridor
While we move done and carrying a box then work done by gravity on the box while our work done is negative work.
C) Pulling a trailer up a hill
In above case our work done to pull a box up a hill is positive work as we need to work against gravity
D) Suspending a heavy weight with a strong chain
During suspension there is no displacement so there will be no work done in above case
so correct answer will be
<em>Pulling a trailer up a hill</em>
The sound is perceived as louder if the amplifier increases, and softer if the amplitude decreases.
Convert 1 atom into 10 electrons (I think)
