Explanation:
Speed of the marathon runner, v = 9.51 mi/hr
Distance covered by the runner, d = 26.220 mile
Let t is the time taken by the marathon runner. We know that the speed of the runner is given by total distance divided by total time taken. Mathematically, it is given by :



t = 2.75 hours
Since, 1 hour = 60 minutes
t = 165 minutes
Since, 1 minute = 60 seconds
t = 9900 seconds
Hence, this is the required solution.
It was Niels Bohr who proposed it
Answer:
Radio stations have dipole type antennas
this field increases in intensity and propagates outwards,
Explanation:
Radio stations have dipole type antennas, that is, all sides are isolated from each other, when the AC signal from the radio station arrives, the lcharge begins at times and by the Lens law a field appears that opposes this movement, this field increases in intensity and propagates outwards, when the voltage reaches a maximum, the generated wave also reaches the maximum, now the incident wave begins to decrease, an electric hand appears to oppose this prisoner, and in this way a cap is created. electric .
Answer:
a. 
b.
must be the minimum magnitude of deceleration to avoid hitting the leading car before stopping
c.
is the time taken to stop after braking
Explanation:
Given:
- speed of leading car,

- speed of lagging car,

- distance between the cars,

- deceleration of the leading car after braking,

a.
Time taken by the car to stop:

where:
, final velocity after braking
time taken


b.
using the eq. of motion for the given condition:

where:
final velocity of the chasing car after braking = 0
acceleration of the chasing car after braking

must be the minimum magnitude of deceleration to avoid hitting the leading car before stopping
c.
time taken by the chasing car to stop:


is the time taken to stop after braking