Mechanical Engineering - Strength of Materials - Discussion
Discussion Forum : Strength of Materials - Section 1 (Q.No. 8)
8.
Two shafts 'A' and 'B' transmit the same power. The speed of shaft 'A' is 250 r.p.m. and that of shaft 'B' is 300 r.p.m. The shaft 'B' has the greater diameter.
Discussion:
52 comments Page 4 of 6.
Govind.T said:
1 decade ago
There is direct relation.
Power(P) = Torque(t)*Angular velocity(w).
(shear stress(s) = 16t/(3.14*d^3).
(w = 2*3.14*n/60).
= s*pi (3.14)*d^3*2*pi*n/60.
Power is directly proportional to d^3 and r.p.m(n).
To get same power for less r.p.m shaft it should have more diameter.
Power(P) = Torque(t)*Angular velocity(w).
(shear stress(s) = 16t/(3.14*d^3).
(w = 2*3.14*n/60).
= s*pi (3.14)*d^3*2*pi*n/60.
Power is directly proportional to d^3 and r.p.m(n).
To get same power for less r.p.m shaft it should have more diameter.
Sunny said:
1 decade ago
P = TW.
T = PI*DN/60.
D = 1/N.
Diameter is inversely proportional to Rpm.
T = PI*DN/60.
D = 1/N.
Diameter is inversely proportional to Rpm.
Prasenjit De said:
1 decade ago
D is inversely proportional to N.
V = I/60 DN.
= V^1/N.
V = I/60 DN.
= V^1/N.
Anil shukla said:
1 decade ago
According to formula Velocity #pi*d*N/60, where d is diameter of shaft, N is speed in rpm. Now N is inversely proportional to 'd'.
Navneet gupta said:
1 decade ago
Equate power of shaft A and shaft B.
On doing this you get Ta = 1.2Tb.
So diameter of B should be smaller.
On doing this you get Ta = 1.2Tb.
So diameter of B should be smaller.
Pravin patel said:
1 decade ago
This mater is depended on shaft diameter but depended on pulley.
OM PRAKASH said:
1 decade ago
(2*pi*n*t)/60 = (2*pi*N*T)/60.
T in the shaft = (pi*tou*d3)/16.
300*d3 = 250*D3.
d3 = (250/300) *D3.
d = 0.94*D.
Then d is smaller than D.
T in the shaft = (pi*tou*d3)/16.
300*d3 = 250*D3.
d3 = (250/300) *D3.
d = 0.94*D.
Then d is smaller than D.
Priya said:
1 decade ago
As speed is inversely proportional to diameter so shaft b has higher speed than its dia must be lower.
Paresh said:
1 decade ago
The torque relation can be obtained from above relation, but not the diameter because, if dia is smaller (as per answer, since torque is less) than even a larger diameter (than dia of shaft A) will be able to sustain that amount of torque.
Though the ' Minimum diameter ' of B will be less than that of A.
Though the ' Minimum diameter ' of B will be less than that of A.
Swapnil said:
1 decade ago
Angular speed is inversely proportional to Torque.
And Torque is directly proportional to radius.
And Torque is directly proportional to radius.
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