- Introduction
- |
- Static Friction
- |
- Kinetic Friction
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- Rolling Friction
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- Angle of Friction
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- Methods to Reduce Friction
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- Solved Examples

A particle of weight W moves under the action of a force

F = A cos ωt

where A and ω are constant at x = 0 and v = 0 at t = 0

The velocity time relation is

The displacement time equation

A pendulum of length l and mass m is supported from the ceiling of the elevator. Let T

(a) elevator is moving up with constant velocity

(b) elevator is moving down with constant velocity

(c) elevator is moving up with constant acceleration

(d) elevator is moving down with constant acceleration

(P) T = T

(Q) T > T

(R) T < T

(S) no appropriate match

Let

S

S

S

S

A block A is at rest as seen from frame of reference S

(a) S

(b) S

(c) S

(d) S

(P) ΣF ≠ 0

(Q) ΣF =0

(R) a = 0

(S) a ≠ 0

where ΣF is the resultant force and a is the acceleration of the body

Consider the figures given below

(a) Acceleration of mass m

(b) Acceleration of mass m

(c) Acceleration of mass m

(d) Acceleration of mass m

(P) (m

(Q) (m

(R) (2m

(S) (m

A,B, C are the objects as shown above in the figure. A, B, C are 2, 3 and 4 Kg respectively. Coefficient of friction between the blocks are given above in the figure

Let f1 be frictional force between A & B

f2 be frictional force between B & C

f3 be frictional force between C & surface

Let a1, a2, a3 be the acceleration of A ,B and C respectively

Which one of the following is true

a) 0≤ f

b) 0≤ f

c) 0≤ f

d) 0≤ f

What is the minimum force F to have so that all part moves with non zero acceleration

(a) 9N

(b) 10N

(c) 14N

(d) 11N

If F = 12 N, which of the following is true

(a) f1 = 11.2, f2 = 10, f3 = 9

a1= a2 = a3 = 0.4 m/s2

(b) f1 = 11.2, f2= 10, f3 = 9

a1 = a2 = 0.25 m/s2, a3 = 0.4 m/s2 (c) f1 = 11, f2 = 10, f3 = 0

a1 = a2 = a3= 0.45 m/s2

(d) none of the above

what is the minimum force required to have relative motion between B & C object

(a) 11.5

(b) 10

(c) 11.25

(d) none of the above

what is the minimum force required to have relative motion between A & B object

(a) 17.5

(b) 16.6

(c) 14

(d) none of the above

for F = 15 N

(a) there will be relative motion between A & B

(b) there will be relative motion between B & C

(c) there will be relative motion between C & surface

(d) none of the above

The pulley is assumed as mass less and friction free.

Find the acceleration of the block assuming no friction is present

(a) F/2m

(b) F/m

(c) 2F/m

(d) none of the above

If friction force F/4 exist between the block and surface

(a) F/m

(b) F/m

(c) F/4m

(d) none of the above

A particle of charge Q and mass M with an initial velocity v0i enter an electric field

What force act in x and y direction

(a) F

(b) F

(c) F

(d) F

Velocity at time t is given by

(a) (v

(b) v

(c) v

(d) none of the above

Let us assume that particle is at origin at t = 0, find the position vector at t = at time t

(a) v

(b) v

(c) (v

(d) none of the above

A block of Mass M rests on smooth horizontal surface over which it can move without friction. A body of mass m lies on the block. The coefficient of friction between body and block is K. The force F acts in horizontal direction on the block

Q

For what values of F, both the bodies will move together without any relative motion

a) 0 ≤ F ≤ kMg

b) 0 ≤ F ≤ kmg

c) 0 ≤ F ≤ k(M+m)g

d) None of these

When the Force F is sufficient to have relative motion between the block and body, what will the acceleration of block and body?

Find the time in which body will fall from the block when relative motion is present. Assume L is the length of the block

A spring balance is attached to the roof of the car and a mass m is hanging from it. When the car is standing on the horizontal road, the balance correctly tells us the weight of the mass. The car is travelling with a constant horizontal velocity v on the undulating path defined by the function

where y is the height above road surface.

Find the weight of the mass in spring balance as function of time t. We can assume that while going up on the undulating surface, the car floor remains almost horizontal

- (b)
- (b)
- (a) → (P);(b) → (P);(c) → (R);(d) → (Q)
- (a) → (Q), (R) ; (b) → (Q), (R) ; (c) → (P), (S) ; (d) → (P), (S)
- (a) → (Q) ; (b) → (P) ; (c) → (P) ; (d) → (R)
- (a)
- (a)
- (b)
- (c)
- (b)
- (c), (b)
- (a)
- (c)
- (a)
- (c)
- (a)
- (c)
- (a)
- (d)
- (d)

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