Finding Friction's Direction
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Q. Two blocks of masses m1 and m2 are connected with a massless unstretched spring and placed over a plank moving with an acceleration a as shown in the figure. The coefficient of friction between the blocks and the platform is μ.
- Spring will be stretched if a>μg
- Spring will be compressed if a≤g
- Spring will neither be stretched nor be compressed for a≤g
- Spring will be in its natural length under all conditions
Q. Two blocks of masses m1 and m2 are connected through a massless inextensible string. Block of mass m1 is placed on the fixed rigid inclined surface, while the block of mass m2 is hanging at the other end of the string, which is passing through a fixed massless frictionless pulley shown in figure. The coefficient of static friction between the block and the inclined plane is 0.8. The system of masses m1 and m2 is released from rest. Take g=10 ms−2
- The tension in the string is 20 N after releasing the system.
- The contact force by the inclined surface on the block is along normal to the inlined surface.
- the magnitude of the contact force by the inclined surface on the block m1 is 20√3 N.
- None of these.
Q. Two blocks of masses m1 and m2 are connected through a massless inextensible string. Block of mass m1 is placed on the fixed rigid inclined surface, while the block of mass m2 is hanging at the other end of the string, which is passing through a fixed massless frictionless pulley shown in figure. The coefficient of static friction between the block and the inclined plane is 0.8. The system of masses m1 and m2 is released from rest. Take g=10 ms−2
- The tension in the string is 20 N after releasing the system.
- The contact force by the inclined surface on the block is along normal to the inlined surface.
- the magnitude of the contact force by the inclined surface on the block m1 is 20√3 N.
- None of these.
Q. A rod is inserted between two boxes as shown in figure. A horizontal force F is applied at the upper end of rod. Then
- box A will move first.
- box B will move first.
- both A and B will move simultaneously.
- can't be predicted.
Q. Two blocks of masses m1 and m2 are connected through a massless inextensible string. Block of mass m1 is placed on the fixed rigid inclined surface, while the block of mass m2 is hanging at the other end of the string, which is passing through a fixed massless frictionless pulley shown in figure. The coefficient of static friction between the block and the inclined plane is 0.8. The system of masses m1 and m2 is released from rest. Take g=10 ms−2
- The tension in the string is 20 N after releasing the system.
- The contact force by the inclined surface on the block is along normal to the inlined surface.
- the magnitude of the contact force by the inclined surface on the block m1 is 20√3 N.
- None of these.
Q. Block A is heavier than Block B in the given case. When they start sliding, the direction of friction for block A is and for block B.
- upward
- downward
- upward
- downward
Q. A tire rolls on a flat road with constant angular velocity ω (in counter clockwise direction) and velocity v (towards left). If v>ωR, in which direction does the friction from the road act on the tire?
- Towards left
- Towards right
- Friction does not act on the tire
- Can't say
Q. In the figure shown, acceleration of the block is
(Take g=10 m/s2)
(Take g=10 m/s2)
- 5.3 m/s2
- zero
- (50√3−410) m/s2
- (5√3−3) m/s2
Q.
A block of mass m is placed on a surface with a vertical cross-section given by y=x36. If the coefficient of friction is 0.5, the maximum height above the ground at which the block can be placed without slipping is
16 m
23 m
13 m
12 m
Q. A body has a velocity of (2i + 3j) m/s. Which of the following vectors is along the direction of friction?
- 2i + 3j
- 2i – 3j
- –2i + 3j
- –2i – 3j
Q.
A girl is standing on ground near a horizontally moving conveyor belt. She throws her suitcase horizontally. Such that the initial velocity of suitcase relative to stationary girl is along dotted line shown in top view of conveyor belt.
Which of the following arrows represents the direction of friction on the bag at the initial moment.
Arrow A
Arrow B
Arrow C
Arrow D
Q. The frictional force acts in the direction on a drop of rain falling down with constant speed.
- upward
- downward
- forward