Help please!!! Thanks!
2 answers:
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Answer:
4 mph
Step-by-step explanation:
The average speed of an object is given by the total distance covered by the time taken:
where
d is the total distance covered
t is the time taken
in the first part, the person runs for 0.4 hours at a speed of 7 mph, so the distance covered in the 1st part is
Then the distance covered in the second part is , so the total distance is
(1)
The total time elapsed is 0.4 hours (first part) + 0.8 hours (second part), so
So we can write the average speed as
(1)
We want the average speed to be 5 mph,
v = 5 mph
Therefore we can rearrange eq.(1) to find d2:
And therefore, the speed in the second part must be
Answer:
a) 3 inch pulley: 11,309.7 radians/min
6) 6 inch pulley: 5654.7 radians/min
b) 900 RPM (revolutions per minute)
Step-by-step explanation:
Hi!
When a pulley wirh radius R rotantes an angle θ, the arc length travelled by a point on its rim is Rθ. Then the tangential speed V is related to angular speed ω as:
When you connect two pulleys with a belt, if the belt doesn't slip, each point of the belt has the same speed as each point in the rim of both pulleys: Then, both pulleys have the same tangential speed:
We need to convert RPM to radias per minute. One revolution is 2π radians, then:
The saw rotates with the same angular speed as the 6 inch pulley: 900RPM