While walking on ice, one should take small steps to avoid slipping. This is because smaller steps ensure:
- ALarger friction.
- ✓Smaller friction.
- CLarger normal force.
- DSmaller normal force.
Answer: B.
View full solution →Question types
Friction question types
57 questions across 6 question groups — pick any mix to generate a Physics paper with step-by-step answer keys.
57
Questions
6
Question groups
5
Question types
01
M.C.Q (1 Marks)
15 Q→021 Marks Question
6 Q→032 Marks Questions
8 Q→043 Marks Question
2 Q→055 Marks Questions
22 Q→06Case study (4 Marks)
4 Q→Sample Questions
Friction questions
One sample from each question group in this chapter. Select any group above to see the full set with answer keys.
Consider a vehicle going on a horizontal road towards east. Neglect any force by the air. The frictional forces on the vehicle by the road:
- Is towards east if the vehicle is accelerating.
- Is zero if the vehicle is moving with a uniform velocity.
- Must be towards east.
- Must be towards west.
- ✓$A$ and $B$
- B$B$ and $C$
- C$A$ and $C$
- D$C$ and $D$
Answer: A.
View full solution →Let $F, F_N$ and f denote the magnitudes of the contact force, normal force and the friction exerted by one surface on the other kept in contact. If none of these is zero:
- $F > F_N$
- $F > f$
- $F_N> f$
- $F_N - f < F < F_N+ f$
- AOnly $A$
- B$A,B$ and $C$
- C$B,C$ and $D$
- ✓$A, B$ and $D$
Answer: D.
View full solution →A block $A$ kept on an inclined surface just begins to slide if the inclination is $30^\circ$ . The block is replaced by another block $B$ and it is found that it just begins to slide if the inclination is $40^\circ :$
- AMass of $A >$ mass of $B.$
- BMass of $A <$ mass of $B.$
- CMass of $A =$ mass of $B.$
- ✓All the three are possible.
Answer: D.
View full solution →Mark the correct statements about the friction between two bodies:
- ALimiting friction is never less than static friction.
- BCoefficient of static friction is always greater than the coefficient of kinetic friction.
- CLimiting friction is always greater than the kinetic friction.
- ✓All of the above
Answer: D.
View full solution →Can a tug of war be ever won on a frictionless surface?
Can you accelerate a car on a frictionless horizontal road by putting more petrol in the engine? Can you stop a car going on a frictionless horizontal road by applying brakes?
What is the average friction force when a person has a usual 1km walk?
Why is it difficult to walk on solid ice?
For most of the surfaces used in daily life, the friction coefficient is less than 1. Is it always necessary that the friction coefficient is less than 1?
Why do tyres have a better grip of the road while going on a level road than while going on an incline?
A classroom demonstration of Newton's first law is as follows: A glass is covered with a plastic card and a coin is placed on the card. The card is given a quick strike and the coin falls in the glass.
- Should the friction coefficient between the card and the coin be small or large?
- Should the coin be light or heavy?
- Why does the experiment fail if the card is gently pushed?
You are standing with your bag in your hands, on the ice in the middle of a pond. The ice is so slippery that it can offer no friction. How can you come out of the ice?
A body slipping on a rough horizontal plane moves with a deceleration of $4.0 \mathrm{~m} / \mathrm{s}^2$. What is the coefficient of kinetic friction between the block and the plane?
View full solution →A block of mass m is kept on a horizontal table. If the static friction coefficient is $\mu,$ find the frictional force acting on the block.
View full solution →A person $(40\ kg)$ is managing to be at rest between two vertical walls by pressing one wall $A$ by his hands and feet and the other wall $B$ by his back. Assume that the friction coefficient between his body and the walls is $0.8$ and that limiting friction acts at all the contacts.
View full solution →- Show that the person pushes the two walls with equal force.
- Find the normal force exerted by either wall on the person. Take $g = 10m/s^2$.
A block is projected along a rough horizontal road with a speed of 10m/s. If the coefficient of kinetic friction is 0.10, how far will it travel before coming to rest?
A body starts slipping down an incline and moves half meter in half second. How long will it take to move the next half meter?
Repeat part (a) of problem 6 if the push is applied horizontally and not parallel to the incline.
A block slides down an inclined surface of inclination 30° with the horizontal. Starting from rest it covers 8m in the first two seconds. Find the coefficient of kinetic friction between the two.
Suppose the block of the previous problem is pushed down the incline with a force of 4N. How far will the block move in the first two seconds after starting from rest? The mass of the block is 4kg.
A block of mass m slips on a rough horizontal table under the action of a horizontal force applied to it. The coefficient of friction between the block and the table is $\mu.$ The table does not move on the floor. Find the total frictional force applied by the floor on the legs of the table. Do you need the friction coefficient between the table and the floor or the mass of the table?
View full solution →A car starts from rest on a half kilometer long bridge. The coefficient of friction between the tyre and the road is $1.0$. Show that one cannot drive through the bridge in less than $10s$.
View full solution →The friction coefficient between an athelete's shoes and the ground is 0.90. Suppose a superman wears these shoes and races for 50m. There is no upper limit on his capacity of running at high speeds.
- Find the minimum time that he will have to take in completing the 50m starting from rest.
- Suppose he takes exactly this minimum time to complete the 50m, what minimum time will he take to stop?
In a children-park an inclined plane is constructed with an angle of incline $45°$ in the middle part. Find the acceleration of a boy sliding on it if the friction coefficient between the cloth of the boy and the incline is $0.6$ and $g = 10m/s^2$.
View full solution →A car is going at a speed of $21.6km/hr$ when it encounters a $12.8m$ long slope of angle $30°$. The friction coefficient between the road and the tyre is $\frac{1}{2\sqrt{3}}.$ Show that no matter how hard the driver applies the brakes, the car will reach the bottom with a speed greater than 36km/hr. Take $g = 10m/s^2$.
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