Newton's Second Law

Q.

A machine gun has a mass of 20 kg fires 35 g bullets at the rate of 400 bullets per second with a speed of 400ms^-1 .What force must be applied to the gun to keep in the position?

1. 5800 N

2. 5600 N

3. 56 N

4. 560 N

Q. A block of mass 10 kg is placed on rough inclinedplane of inclination angle 37. Coefficient of frictionbetween block & plane is 0.8, find minimummagnitude of F so that block remains at rest.

Q. A machine gun has a mass 5 kg. It fires bullets ofmass 50 g each at the rate of 30 bullets/minute witha speed of 400 m/s. Force required to hold the gunin position isnmy30X5(1) 150 N(2) 15 N(3) 10N14) 20 N

Q. A block of mass M rests on a rough horizontal surface. Coefficient of friction between the block and the surface is μ. A force F=Mg acting at angle θ with the vertical side of the block pulls it. In which of the following cases the block can be pulled along the surface:- (A)†anθ≥μ (B)†an(θ/2)≥μ (C)cotθ≥μ (D)cot(θ/2)≥μ

Q. A constant force F has been applied upon the plank of mass M. Upon plank, a thin circular wheel of mass m and radius R has been placed. There is no slipping between plank and wheel. The friction force upon wheel will be?

Q.

A block of mass 50 kg can slide on a rough horizontal surface. The coefficient of friction between the block and the surface is 0.6. The least force of pull acting at an angle of ${30}^o$ to the upward drawn vertical which causes the block to just slide is

1. 219.6 N

2. 21.96 N

3. 294.3 N

4. 29.43 N

Q. A machine gun of mass 50g with velocity 1000m/s. If average force acting on gun is 200N then find out the max number of bullets fired per minute.

Q.

A block of mass $4kg$ slides down a plane inclined at ${37}^{\circ }$ with the horizontal. The length of plane is $3m$. The coefficient of sliding friction between the block and the plane is $0.2$. Find the work done by gravity and the frictional force on the block.

1. 0J, -18.816 J

2. -70.56J, 0J

3. 70.56J , -18.816 J

4. None of these

Q. P.A force P= 3mg acts on a block of mass m at an angle of 30^° with horizontal. The friction force betweenthe block and ground (assuming u = coefficient of friction between the contacting surface) isP = 3mg1130^° Car 30m22

Q. Two blocks of masses 5kg and 4kg are in contact with each other on a frictionless table. When a horizontal force of 9N is applied to the block of mass 5kg, then the value of the force of contact between the two blocks is?

Q. 7. A long thin carpet is laid on the floor. One enti of the carpet is bent back and then pulled backwards with constant velocity v# 4 ms just above the carpet, the remaining part of carpet remains at rest on the foor The velocity of instantaneous centre of mass of the moving part of carpet is 4 m/s TTITITTIIIT7 (1) 3/4 m/s (3) 2 m/s (2) 413 m/s (4) 3 m/s

Q. A body of mass 2 kg has an initial velocity $v_i=(\hat{i}+\hat{j})m{s}^{-1}$. After collision with another body its velocity becomes $v_f=(5\hat{i}+6\hat{j}-\hat{k})m{s}^{-1}$. If the impact time is 0.02 s, the average force of impact on the body (in newton) is

1. $50(4\hat{i}+5\hat{j}+\hat{k})$
2. $50(4\hat{i}-5\hat{j}-\hat{k})$
3. $100(4\hat{i}+5\hat{j}-\hat{k})$
4. $100(4\hat{i}+5\hat{j}-\hat{k})$

Q. Two masses of 0.25 kg moving towards each other with speed 3 and 1 m/s collide and stick together Find the final velocity

Q. A particle of mass 2kg is moving along AB according tp y= x-4 with speed 4m/s, then magnitude of angulr momentum about o is (a) 16\sqrt2 kg m^2/s (b) 32\sqrt2 kg m^2/s (c) 32 kg m^2/s (d) 16 kg m^2/s

Q. a particle of mass 2m moving with velocity v strikes a stationary particle of mass 3m and sticks to it. the speed of the system is

Q. A 2Kg block is kept on a 4Kg block which is kept on a frictionless table coefficient of friction between 2Kg and 4kg block is 0.2 if a force of 5N is applied on 2Kg block then find the acceleration of each bloc

Q.

A child weighing 30 kg slides down a rope hanging from the branch of a tall tree. If the force of friction acting against him is 2 N, what is the acceleration of the child (Take g = 10m / s.)

Q. 24.In the given figure the pulley is assumed massless and frictionless. If the friction force on the object of mass m is f , the its acceleration in terms of the force F is A) F-f/m B) (0.5F-f )/m C) F/m D) none of these

Q. 17.A plank having mass M is placed on smooth horizontal surface. Block of mass m is placed on it coefficient of friction between block and plank is 0 kx , where k is constant and x is relative displacement between block and plank. A force F is applied on block where F = at, where a = 10; t is in second. Find t0 when relative motion will occur between block and plank

Q. A particle of mass 1 kg has been thrown with initil speed 20 m/s making an angle 60 with the horizontal ground. The angular momentum of the particle about point of projection when the projectile is at the highest point is (g 10 m/s2)

Q.

Starting from rest, a body slides down a ${45}^o$ inclined plane in twice the time it takes to slide down the same distance in the absence of friction. The coefficient of friction between the body and the inclined plane is

1. 0.25

2. 0.33

3. 0.75

4. 0.80

Q. 33.A block of mass m =2kg is resting on the rough inclined plane of inclination 30degree. The coefficient of friction between the block and the plane is 0.5.What minimum force F should be applied perpendicular to the plane on the block, so that block does not slip on the plane

Q. 31.Two block A and B placed on a plane surface as shown in attachment. The mass of block A is 100 kg and that of block B is 200 kg. Block A is tied to a stand and block B is pulled by a force F. If the coefficient of friction between the surface A and B is 0.2 and the coefficient of B and the plane is 0.3 then for the motion of B the minimum value of F will be A) 700 N B) 1050 N C) 900 N D) 1100N

Q. find the relation between torque and angular momentum.

Q.

What happens to the coefficient of friction when weight of the body is doubled?

Q.

fig. Shows the variation of force acting on a body with time. Assuming the body to start from rest, the variation of its momentum with time is best represented by which plot?

1. 

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4. 

Q. A shell of mass 0.02kg is fired by a gun of mass 100 kg. The muzzle speed of the shell is 80 m s^{-1}.Find the recoil speed of the gun.

Q. A block of mass m is placed on another block of mass M.The coefficient of friction between two blocks is u1 and that between the block of mass M and horizontal surface is up. What maximum horizontal force can be applied to the lower block so that the two blocks move without separation

Q. 57.A block of mass m rests on an inclined plane which is making angle x with the horizontal.The coefficient of friction between the block and plane is n.Then the frictional force acting between the surfaces is___?

Q. 11. A system consists of three masses m, m2 and m3connected by a string passing over a pulley P Themass m hangs freely and m, and m are on arough horizontal table (The coefficient of frictionu). The pulley is frictionless and of negligiblemass. The downward acceleration of mass m, is:(Assume m, = m2 = m3 = m)( -u u\lbrack AIPMT-2014\rbrack(r16-1)6(L)6ri2(Z)(3) g(1-2u)g (1-2u)(1)