Answer:
v = 37.59 km/h
Explanation:
The question says, "how fast in km / h did usain bolt run at the berlin world championship in 2009 to break the world record for the 100m sprint in 9.58".
Distance, d = 100 m = 0.1 km
Time, t = 9.58 s = 0.00266 h
We need to find the speed of the Usain Bolt. We know that,
Speed = distance/time
So,
So, the required speed is equal to 37.59 km/h.
Solution :
Given
Diameter of the roulette ball = 30 cm
The speed ball spun at the beginning = 150 rpm
The speed of the ball during a period of 5 seconds = 60 rpm
Therefore, change of speed in 5 seconds = 150 - 60
= 90 rpm
Therefore,
90 revolutions in 1 minute
or In 1 minute the ball revolves 90 times
i.e. 1 min = 90 rev
60 sec = 90 rev
1 sec = 90/ 60 rec
5 sec =
= 75 rev
Therefore, the ball made 75 revolutions during the 5 seconds.
Explanation:
Let be the airspeed.
Let be the cross wind speed.
We know that,ground speed is the vector sum of airspeed and cross wind speed and airspeed is perpendicular to cross wind speed.
If and
are two perpendicular vectors,the resultant vector has the magnitude
Given,
So,the ground speed is
Answer:
answer is 0m/ sec
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