# Try to solve this problem !

#### Jonasxx

Joined Nov 5, 2018
2
Drill used in the manufacture of the engine parts is designed to have seven speeds. The range of hole sizes anticipated is from 6mm to 25mm.
You have been asked to determine the six spindle speeds (rev/min) given that the cutting speed is 20m/min.

These spindle speeds are to be arranged in:
a) arithmetic progression
b) geometric progression

Note: N=1000s/pi x D, N=spindle speed (rev/min), s=cutting speed (m/min), D=hole diameter (mm)

#### ericgibbs

Joined Jan 29, 2010
9,531
hi Jona,
Welcome to AAC.
Is this a College or Homework assignment, I see that you are a Student.?
E

#### wayneh

Joined Sep 9, 2010
16,235
These spindle speeds are to be arranged in:
a) arithmetic progression
b) geometric progression
I'd start by determining the minimum and maximum. Then you can fill in the other values based on the type of progression. You have everything you need, right?

#### Jonasxx

Joined Nov 5, 2018
2
What i need to find first ?

You are investigating the electrical testing circuits and find that, in an inductive circuit, the relationship between instantaneous current i (amps)
and the time t (secs) is given by:

i = 2.1(1-e-9t)
You have been asked to determine the time taken for the current to rise from 1 to B amps.

Thanks