Answer:
43.2 N
Explanation:
= Wavelength = 0.75 m
f = Frequency = 40 Hz
m = Mass of string = 0.12 kg
L = Length of string = 2.5 m
= Linear density = 
Velocity of wave is given by

The tension in string is given by

The tension in the string is 43.2 N
Answer:
Explanation:
Let the potential difference between the middle point and one of the plate be ΔV .
electric potential energy will be lost and it will be converted into kinetic energy .
Electrical potential energy lost = Vq , where q is charge on charge particle .
For proton
ΔV× q = 1/2 M V² ( kinetic energy of proton )
where M is mass and V be final velocity of proton .
For electron
ΔV× q = 1/2 m v² ( kinetic energy of electron )
where m is mass and v be final velocity of electron . Charges on proton and electron are same in magnitude .
As LHS of both the equation are same , RHS will also be same . That means the kinetic energy of both proton and electron will be same
1/2 M V² = 1/2 m v²
(V / v )² = ( m / M )
(V / v ) = √ ( m / M )
In other words , their velocities are inversely proportional to square root of their masses .
as per the question charlie runs to the store which is 4 km away
hence the total distance covered [S] is 4 km
he takes 30 minutes to reach the store.
hence the total time taken [t] = 30 minutes=0.5 hour
We have to calculate the average speed.
the average speed[v]= 
=
=8 km/hour
then we have to calculate the total distance traveled by charlie in 1 hour.
the distance covered S= 
=8 km/hour ×1 hour
=8 km
Hence the average speed of charlie is 8 km/hour and he covers a distance of 8 km in 1 hour.