MPE 242 - MECHANICS OF MACHINES II, CAT 2, COLLECTION: 28/04/22 AT 5PM
1) A racing car weighs 20 kN. It has a wheel base of 2 m, track width 1 m and height of C.G.
300 mm above the ground level and lies midway between the front and rear axle. The
engine flywheel rotates at 3000 r.p.m. clockwise when viewed from the front. The
moment of inertia of the flywheel is 4 kg-m2 and moment of inertia of each wheel is 3
kg-m2. Find the reactions between the wheels and the ground when the car takes a curve
of 15 m radius towards right at 30 km / h, taking into consideration the gyroscopic and
the centrifugal effects. Each wheel radius is 400 mm. [10mks]
2) A cast iron flywheel used for a four stroke I.C. engine is developing 187.5 kW at 250
r.p.m. The hoop stress developed in the flywheel is 5.2 MPa. The total fluctuation of
speed is to be limited to 3% of the mean speed. If the work done during the power stroke
is 1/3 times more than the average work done during the whole cycle, find: 1. mean
diameter of the flywheel, 2. mass of the flywheel and 3. cross-sectional dimensions of the
rim when the width is twice the thickness. The density of cast iron may be taken as 7220
kg/m3. [10mks]
3) The upper arms of a Porter governor are pivoted on the axis of rotation and the lower
arms are pivoted to the sleeve at a distance of 30 mm from the axis of rotation. The length
of each arm is 300 mm and the mass of each ball is 6 kg. If the equilibrium speed is 200
r.p.m. when the radius of rotation is 200 mm, find the required mass on the sleeve. If the
friction is equivalent to a force of 40 N at the sleeve, find the coefficient of insensitiveness
at 200 mm radius. [10mks]
1) A racing car weighs 20 kN. It has a wheel base of 2 m, track width 1 m and height of C.G.
300 mm above the ground level and lies midway between the front and rear axle. The
engine flywheel rotates at 3000 r.p.m. clockwise when viewed from the front. The
moment of inertia of the flywheel is 4 kg-m2 and moment of inertia of each wheel is 3
kg-m2. Find the reactions between the wheels and the ground when the car takes a curve
of 15 m radius towards right at 30 km / h, taking into consideration the gyroscopic and
the centrifugal effects. Each wheel radius is 400 mm. [10mks]
2) A cast iron flywheel used for a four stroke I.C. engine is developing 187.5 kW at 250
r.p.m. The hoop stress developed in the flywheel is 5.2 MPa. The total fluctuation of
speed is to be limited to 3% of the mean speed. If the work done during the power stroke
is 1/3 times more than the average work done during the whole cycle, find: 1. mean
diameter of the flywheel, 2. mass of the flywheel and 3. cross-sectional dimensions of the
rim when the width is twice the thickness. The density of cast iron may be taken as 7220
kg/m3. [10mks]
3) The upper arms of a Porter governor are pivoted on the axis of rotation and the lower
arms are pivoted to the sleeve at a distance of 30 mm from the axis of rotation. The length
of each arm is 300 mm and the mass of each ball is 6 kg. If the equilibrium speed is 200
r.p.m. when the radius of rotation is 200 mm, find the required mass on the sleeve. If the
friction is equivalent to a force of 40 N at the sleeve, find the coefficient of insensitiveness
at 200 mm radius. [10mks]
