Laws of Motion

In the given figure the blocks A, B and C weigh 4 kg, 6 kg and 8 kg respectively. The coefficient of sliding friction between any two surfaces is 0.5. The force F required to slide the block C with constant speed is N. (Use g = 10 m/s2) [figure]

A flexible chain of mass m hangs between two fixed points at the same level. The inclination of the chain with the horizontal at the two points of support is 30 . Considering the equilibrium of each half of the chain, the tension of the chain at the lowest point is .

1. mg
2. 32mg
3. 12mg
4. 3mg

A block is sliding down on an inclined plane of slope and at an instant t = 0 this block is given an upward momentum so that it starts moving up on the inclined surface with velocity u. The distance (S) travelled by the block before its velocity becomes zero, is . (g = gravitational acceleration)

1. 2u2g
2. u2 2g
3. u22g
4. u22g

A body of mass 14 kg initially at rest explodes and breaks into three fragments of masses in the ratio 2 : 2 : 3. The two pieces of equal masses fly off perpendicular to each other with a speed of 18 m/s each. The velocity of the heavier fragment is m/s.

1. 24 2
2. 12
3. 12 2
4. 10 2

A 4 kg mass moves under the influence of a force F = (4t3 i - 3t j) N where t is the time in second. If mass starts from origin at t = 0, the velocity and position after t = 2 s will be:

1. v = 3 i + 32 j r = 65 i + j
2. v = 4 i - 32 j r = 65 i - j
3. v = 4 i - 32 j r = 85 i - j
4. v = 4 i + 52 j r = 85 i + 2 j

A large drum having radius R is spinning around its axis with angular velocity , as shown in figure. The minimum value of so that a body of mass M remains stuck to the inner wall of the drum, taking the coefficient of friction between the drum surface and mass M as , is : [figure]

1. 2g R
2. g2 R
3. gR
4. g R

A body of mass 2 kg moving with velocity of vin = 3 i + 4 j m s-1 enters into a constant force field of 6 N directed along positive z-axis. If the body remains in the field for a period of 53 seconds, then velocity of the body when it emerges from the force field is:

1. 3 i + 4 j + 5 k
2. 4 i + 3 j + 5 k
3. 3 i + 4 j - 5 k
4. 3 i + 4 j + 5 k

A cubic block of mass m is sliding down on an inclined plane at 60 with an acceleration of g2, the value of coefficient of kinetic friction is

1. 32
2. 23
3. 1 - 32
4. 3 - 1

An object with mass 500 g moves along x-axis with speed v = 4 x m/s. The force acting on the object is :

1. 8 N
2. 4 N
3. 5 N
4. 6 N

A body of mass m is suspended by two strings making angles 1 and 2 with the horizontal ceiling with tensions T1 and T2 simultaneously. T1 and T2 are related by T1 = 3T2, the angles 1 and 2 are

1. 1 = 30 , 2 = 60 with T2 = 3mg4
2. 1 = 45 , 2 = 45 with T2 = 3mg4
3. 1 = 30 , 2 = 60 with T2 = 4mg5
4. 1 = 60 , 2 = 30 with T2 = mg2