Laws of Motion · Question 3

A block takes t time to slide down a plane inclined at 45° to the horizontal. If the surface is made smooth (frictionless), the block takes time t2 to slide down the plane. The coefficient of friction between the block and the inclined plane is ( 100 ). The value of is .

Three masses m1=4 kg, m2=4 kg and m3=6 kg are suspended from a fixed smooth frictionless pulley as shown in the figure below. The value of T1/T2 is . (take g=10 m/s2) [figure]

1. 5/3
2. 2/3
3. 3/5
4. 2/5

A wedge Y with mass of 10 kg and all frictionless surfaces and the inclined surface making 37° with horizontal. A block X with mass 2 kg is placed at the highest point of the wedge as shown in figure is at rest. At t=0 wedge (Y) is pulled toward right with constant force (f) of 24 N. Taking the block X at rest at t=0, the time taken by it to slide down 8.8 m on the slope, while Y is on the move, is s. (take tan (37°) = 3/4 and g = 10 m/s2) [figure]

1. 2
2. 4
3. 2
4. 2 2

The time taken by a block of mass m to slide down from the highest point to the lowest point on a rough inclined plane is 50 % more compared to the time taken by the same block on identical inclined smooth plane. Both inclined planes are at 45° with the horizontal. The coefficient of kinetic friction between the rough inclined surface and block is .

1. 3/4
2. 2/3
3. 5/9
4. 4/9

At t=0, a body of mass 100 g starts moving under the influence of a force (5 i+10 j ) N. After 2 s its position is (2x i+5y j ) m. The ratio x:y is .

1. 1 : 2
2. 2 : 5
3. 5 : 2
4. 5 : 4

A 0.5 kg mass is in contact against the inner wall of a cylindrical drum of radius 4 m rotating about its vertical axis. The minimum rotational speed of the drum to enable the mass to remain stuck to the wall (without falling) is 5 rad/s. The coefficient of friction between the drum's inner wall surface and mass is . (Take g=10 m/s2)

1. 0.1
2. 0.5
3. 0.7
4. 0.3

A block of mass 5 kg is moving on an inclined plane which makes an angle of 30 with the horizontal. Friction coefficient between the block and inclined plane surface is 32. The force to be applied on the block so that the block will move down without acceleration is N. (g = 10 m/s2).

1. 25
2. 12.5
3. 15
4. 7.5

A small block of mass m slides down from the top of a frictionless inclined surface, while the inclined plane is moving towards left with constant acceleration a0. The angle between the inclined plane and ground is and its base length is L. Assuming that initially the small block is at the top of the inclined plane, the time it takes to reach the lowest point of the inclined plane is . [figure]

1. 2Lg - a0
2. 4Lg 2 - a0(1 + 2 )
3. 2Lg 2 - a0(1 + 2 )
4. 4Lg 2 - a0

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