The power of an engine is frequently determined experimentally with the aid of the so-called absorption dynamometer which consists of two shoes tightly gripping the shaft of the engine. A lever with a weight on the end is attached to one of the shoes (Fig.). The weight is selected so as to equalize the force of friction and hold the lever in a horizontal position.
Determine the power of the engine if the number of shaft revolutions is n = 60 rpm, the length of the lever from the centre of the shaft is λ = 1m and the weight Q = 50 kgf. Disregard the weight of the lever.
Text Solution
Verified by ExpertsCHECK THE SOLUTION.
Sol. The force of friction F between the shoes and the shaft is determined from the equilibrium condition of the lever in the absorption dynamometer: the moment of the force F is equal to the moment of the force Q:
Fr = Q λ
and hence F = 
The velocity of the points on the surface of the shaft will be
v = 2 π fr
where f = 
is the number of shaft revolutions per second
N = Fv = 
= 2 π Qv λ ≈ 4.2 hp
Prepare Smarter with CGP Edu
Get practice questions, solutions, and test series in one place.
Write a Review
Share your experience with this question and solution.
Commentary
Send your comment, doubt, correction, or feedback to admin.
Similar Questions
Explore conceptually related problems