Answer:
Metallic plates emit electrons only when light of a certain minimum frequency shines on them.
Explanation:
Answer:
8.57 m/s
Explanation:
let's list out available parameters:
Initial velocity, u = 20 m/s
Time = 15 - 1 = 14 s
Distance, s = 200 m
Final velocity = ?
We are assuming a uniformly accelerated motion.
Using one of the equations of motion
m/s
To stop just as the light turns green, the motorist needs to decelerate in a controlled manner. The effective time to cover the distance after seeing the red light is 14 seconds, disregarding the 1 second it takes to react and press the brakes. Therefore, as she reaches the traffic signal when it turns green, her speed is 0 m/s.
This situation can be approached using the concept of kinematics in Physics. To solve it, we need to consider total time and total distance traveled. The motorist is driving towards the traffic light, which is 200m away, and the light stays green for 15 seconds. However, since it takes her 1 second to step on the brakes, effectively, she has 14 seconds to travel to the light.
Since she starts braking the car, she begins to decelerate. While decelerating, time is the only determinant of the distance covered, not the speed. As she reaches the light, the speed would be zero regardless of the initial speed or distance if the deceleration is constant. So, when the light turns green, her speed will be 0 m/s.
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