1. Choose the correct answer from the given alternatives.
A force P of 50 N and another force Q of unknown magnitude act at 90° to each other. They are balanced by a force of 130 N. The magnitude of Q is
60 N
80 N

(iii) 100 N
120 N The centre of gravity of a hemisphere of radius r from its base measured along the vertical radius is 4r/3

(ii) 3r/2

(iii) 3r/8

(iv) 4r/7

(c) Area moment of inertia of a square section of side "a" about its base is

(ii)

(iii)

(iv) The maximum value of the horizontal range for a projectile projected with a velocity of 98 m/sec is 98m

(ii) 490m

(iii) 980m

(iv) 1960m Relation between tangential velocity "ut" and angular velocity "w" of a body in circular motion is
ut rw

(ii) w utr

(iii) r utr
None of the above
Which of the following is a scalar quantity Energy

(ii) Momentum

(iii) Torque
Impulse
A system of coplanar forces acting on a rigid body can be reduced to
one force only

(ii) one couple only

(iii) one force and one couple only
None of the above

2.(a) Four forces are acting at 0 as shown in Figure 1. Find the resultant in magnitude and direction by using method of resolution of forces.

<img src='./qimages/15356-2a.jpg'>

(b) State triangle law of forces and polygon law of forces.

3. Find the moment of inertia of the hollow section shown in Figure 2 about its centroidal axis XOX.

<img src='./qimages/15356-3.jpg'>

4. List the various methods of analyzing a truss. Find the forces in Warren truss by any method from Figure 3.

<img src='./qimages/15356-4.jpg'>

5. A body weighing 400 N is resting on an inclined plane making an angle of 300 with the horizontal. A force P is applied parallel to and up the inclined plane. Find the least value of P when the body is just on the point of movement moving up. Consider coefficient of friction is 0·3.

6. A wheel of 1 m diameter is mounted on a shaft between two bearings. The wheel is subjected to constant moment of 100 Nm at the rim for 10 minutes to attain a speed of 120 rpm. Calculate the following: The number of revolutions made during this period
The angular acceleration, the tangential acceleration and centripetal acceleration
The work done in rotating the wheel during this time

7. Body A is thrown with a velocity of 10 m/s at an angle of 600 to the horizontal. If another body B is thrown at an angle of 450 to the horizontal, find the velocity, if it has the same horizontal range

(b) maximum height

(c) time of flight, as the body A.