Hi all! was wondering if anybody could help me out with the method for this question.....

 

Ive got a physics for chemists test tommorrow in uni since I havn't done A-Level Physics before. Ive been going through a couple of questions as part of my revision which most of them I have been getting the right answers...

 

Ive just recentely come across this question and its really puzzling me how to get to the right answer....

 

Question

 

The blades of a rotary lawn mower are 0.25 m in radius and have a maximum rotation rate of 3,700 revoultions per minute. Calculate the velocity at the tip of the blade at the maximum rotation rate.

 

[Answer: 97 m/s]

 

All replies would be gratefully appreciated...Thanks

Hi all! was wondering if anybody could help me out with the method for this question.....

 

Ive got a physics for chemists test tommorrow in uni since I havn't done A-Level Physics before. Ive been going through a couple of questions as part of my revision which most of them I have been getting the right answers...

 

Ive just recentely come across this question and its really puzzling me how to get to the right answer....

 

Question

 

The blades of a rotary lawn mower are 0.25 m in radius and have a maximum rotation rate of 3,700 revoultions per minute. Calculate the velocity at the tip of the blade at the maximum rotation rate.

 

[Answer: 97 m/s]

 

All replies would be gratefully appreciated...Thanks

Draw a circle with a radius of .25m (or draw a scaled down version of it)

 

Firstly, 1 revolution means going around the circle once.

Going around the circle once means traveling its circumference.

The circumference of a circle is 2*pi*1/4 m

 

Secondly, the blade goes at 3700 revolutions per minute.

Therefore, the blade goes 3700 (2*pi*.25m)/ 1 minute

 

Just convert by multiplying it by (1 minute / 60 seconds) to get m/s units. Take 2 significant digits.

Draw a circle with a radius of .25m (or draw a scaled down version of it)

 

Firstly, 1 revolution means going around the circle once.

Going around the circle once means traveling its circumference.

The circumference of a circle is 2*pi*1/4 m

 

Secondly, the blade goes at 3700 revolutions per minute.

Therefore, the blade goes 3700 (2*pi*.25m)/ 1 minute

 

Just convert by multiplying it by (1 minute / 60 seconds) to get m/s units. Take 2 significant digits.

Awww thank you so much youv'e been a great help!

Awww thank you so much youv'e been a great help!

No problem.