D.
50 mph - 30 mph= 20 mph net velocity
change.
20mph/3600 seconds/hour= .00555 MPS
.0055 miles per second
40 seconds to complete the change
.0055/40= .000138
Answer:
Figure A
Explanation:
At first, the inflated balloon is rubbed against the hair.
In this situation, the balloon is charged by friction: because of the friction between the surface of the balllon and the hair, electrons are transferred from the hair to the surface of the balloon.
As a result, when the balloon is detached from the hair, it will have an excess of negative charge (due to the acquired electrons).
Then, the balloon is placed in contact with the non-conducting wall.
The non-conducting wall is initially neutral (equal number of positive and negative charges).
Because the wall is made of a non-conducting material (=isolant), the charges cannot move easily through it. Therefore, even though the charges on the wall feel a force due to the presence of the electrons in the balloon, they will not redistribute along the wall.
Therefore, the charges on the wall will remain equally distributed, as shown in figure A.
C. The higher the altitude the less gravity affects you
Answer:
skateboard b
Explanation:
p=mv
skateboard a
p=(60kg)(1.5m/s)=90kg*m/s
skateboard b
p=(50kg)(2m/s)=100kg*m/s
