EM Assinment 2

Department of Mechanical Engineering, MITS-FET Engineering Mechanics (ME-105) Tutorial. Autumn Semester 2011-2012

Name: Batch: Roll No.:

Engineering Mechanics (ME 105) TUTORIAL SHEET-2

1 2 3 4

Define and Explain the moment of a force. Differentiate between clockwise and anticlockwise moment. State the Varignon’s principle. What is a couple? Calculate the moment of the 400 N force about point O in four different way

Ans. MO = 33.6 N

5

Replace the force and couple acting on the wrench by a single equivalent force F applied at D. Determine b.

Ans. D = 0.2 m, b = 213 mm 6

A 90-N force is applied to the control rod AB as shown. Knowing that the length of the rod is 225 mm, determine the moment of the force about point B by resolving the force into components along AB and in a direction perpendicular to AB.

Ans. MB = 13.02 N.M

7

Ans. 46.4 Nm CW

8

A sign is suspended from two chains AE and BF. Knowing that the tension in BF is 200 N, determine (a) the moment about A of the force exerted by the chain at B, (b) the smallest force applied at C which creates the same moment about A. Ans. MA = 386 N.m CCW FC = 160.1 N

9

A 135-N vertical force P is applied at A to the bracket shown, which is held by screws at B and C. (a) Replace P with an equivalent force couple system at B. (b) Find the two horizontal forces at B and C that are equivalent to the couple obtained in part a. a) FB = 135 N , MB = 16.88 N.m ccw b) FB = 225 N FC = 225 N

10

A 700-N force P is applied at point A of a structural member. Replace P with an equivalent force-couple system at C

MC = 585 N.m ccw

11

Determine and locate the resultant R of the two forces and one couple acting on the I beam. Ans. R = 3 KN download, MO =1 kN m cw d = 1/3 m, X = 4.33 m

12

If the resultant of the two forces and couple M passes through point O, determine M.

M = 148 N.M

13

A force and a couple are applied to a beam. (a) Replace this system with a single force F applied at point G, and determine the distance d. (b) Solve part a assuming that the directions of the two 150-lb forces are reversed.

Ans. F= 200 N d= 9 m, 0 m 14

The tool at A is used to hold a power lawnmower blade stationary while the nut is being loosened with the wrench. If a force of 50 N is applied to the wrench at B in the direction shown, determine the moment it creates about the nut at C. What is the magnitude of force F at A so that it creates the opposite moment about C?

Ans. 13.0 Nm, 35.2 Nm 15

The masses of two children sitting at ends A and B of a seesaw are 38 kg and 29 kg, respectively. Determine where a third child should sit so that the resultant of the weights of the three children will pass through C if she has a mass of (a) 27 kg, (b) 24 kg.

16

Pulleys A and B are mounted on bracket CDEF. The tension on each side of the two belts is as shown. Replace the four forces with a single equivalent force, and determine where its line of action intersects the bottom edge of the bracket

17

By driving a truck over a scale, it was determined that the loads on the front and rear axles are 18 kN and 12 kN, respectively, when the truck is empty. Determine the weight and the location of the heaviest load that the truck can carry if the load on each axle is not to exceed 40 kN.