Bunuel
In a certain mega-shopping mall, Carla and Daniel start from the beginning of a 200-meter-long moving walkway and move in the same direction as the walkway, which travels at a constant speed of 0.5 meters per second.
- Carla starts running at a constant rate of 1 meter per second relative to the walkway, continues running for exactly 40 seconds, and then stops running for x seconds. While not running, Carla stands still and is carried only by the walkway.
- Afterward, she resumes running at 1.5 meters per second relative to the walkway for exactly 5 seconds, at which point she reaches the end of the walkway.
- Daniel walks at a constant rate of 0.5 meter per second relative to the walkway, from start to finish without stopping, and reaches the end in y seconds.
Select for
x and
y the value of of x and y, that are consistent with the information provided. Make only two selections, one in each column.
The walk way is 200 meter long and it’s moving at a constant speed of 0.5 meters per second.
Speed of walkway W = 0.5 m/s
Carl running at a constant speed of 1 m/s.
For 40 seconds, relative speed = (1+0.5) = 1.5 * 40 = 60 metres.
While stopped running, the speed of Carl is zero, only walkway speed (0.5 m/s) acts on for those x seconds.
She again runs for 5 seconds at 1.5 m/s. So, the relative speed = (1.5+ 0.5) = 2 m/s * 5 = 10 metres.
Total distance = 200 metres.
Distance now covered running = 60+10 = 70 metres. Remaining distance = 200 - 70 = 130 metres.
For covering 130 metres at speed 0.5 m/s takes, 130/0.5 =
260 seconds. X =
260 seconds. Daniel walks at rate 0.5 m/s, then the relative speed = (0.5+0.5) = 1 m/s
1 m/s = 200 m / ( time in seconds )
time = 200 seconds.
y = 200 seconds