Answer:
The magnitude and direction of electric field midway between these two charges is
along AB.
Explanation:
Given that,
First charge 
second charge 
Distance = 20 cm
We need to calculate the electric field
For first charge,
Using formula of electric field

Put the valueinto the formula


Direction of electric field along AB
We need to calculate the electric field
For second charge,
Using formula of electric field

Put the valueinto the formula


Direction of electric field along AO
We need to calculate the net electric field at midpoint



Direction of net electric field along AB
Hence, The magnitude and direction of electric field midway between these two charges is
along AB.
Answer: send the message underwater because a more dense medium would make the sound travel faster.
Explanation:
Dolphins communicate using compression waves - longitudinal waves. Longitudinal waves requires a medium to travel. A longitudinal wave transfers energy by the vibration of medium particles in the direction of the wave motion. Compression are the regions where density of the medium is higher and rarefaction is a low density region.
A longitudinal wave travels faster in a denser medium. It has maximum speed in solid and minimum in gas. Thus, to transfer message quickly to dolphin B., dolphin A should send the message underwater and not in air. This is because water has higher density than air. Molecules collide more quickly in water than in air and it takes less time for signal to travel.
Explanation:
It is given that,
Speed of the sports car, v = 85 mph = 37.99 m/s
The radius of curvature, r = 525 m
Let
is the normal weight and
is the apparent weight of the person. Its apparent weight is given by :

So, 



or

Hence, this is the required solution.