With reference to the motion of a bicycle, consider the following statements: 1. When pedalling stops, the bicycle slows down solely due to the absence of the pedalling force. 2. To keep the bicycle moving at a uniform velocity, the applied force must balance the frictional force. 3. An object moves with a uniform velocity when the pushing force is greater than the frictional force. Which of the statements given above is/are correct?

Correct Option The correct option is (b). Explanation The Newton's Laws of Motion, specifically analyzing the relationship between applied force, friction, and the resulting state of motion (acceleration vs. uniform velocity). Statement-wise Analysis - Statement 1 is Incorrect. According to Newton's First Law of Motion (Law of Inertia), an object in motion will continue moving at the same speed unless acted upon by an external unbalanced force. When pedalling stops, the bicycle slows down not merely because the pedalling force is absent, but because of the presence of retarding forces such as friction (between the tyres and the road) and air resistance. If these opposing forces were absent, the bicycle would continue moving perpetually even without pedalling. - Statement 2 is Correct. To move an object at a uniform velocity, the net force acting on it must be zero (since acceleration is zero). This requires the applied force (pedalling) to exactly balance the opposing frictional force. In this state of equilibrium, the forces cancel each other out, maintaining constant speed. - Statement 3 is Incorrect. If the pushing force is greater than the frictional force, there is a net unbalanced force acting in the direction of motion. According to Newton's Second Law ($F = ma$), a net force produces acceleration. Consequently, the velocity of the object would increase, and it would not move with a uniform velocity. Key Takeaway: Uniform velocity implies zero acceleration, which occurs only when the net force on an object is zero. This happens when the driving force is exactly equal and opposite to the resistive forces (friction).

With reference to the motion of a bicycle,… - NCERT Class 9 Science MCQ

NCERT Class 9 Science — Chapter 2: Force and laws of motion

mcqhard

With reference to the motion of a bicycle, consider the following statements:

When pedalling stops, the bicycle slows down solely due to the absence of the pedalling force.
To keep the bicycle moving at a uniform velocity, the applied force must balance the frictional force.
An object moves with a uniform velocity when the pushing force is greater than the frictional force.

Which of the statements given above is/are correct?

NCERT textbook question

From NCERT Science - class 9 · Page 2

Options

A1 only
B2 only
C1 and 3 only
D1, 2 and 3

Did you get this right?

Solution

Correct Option

The correct option is (b).

Explanation

The Newton's Laws of Motion, specifically analyzing the relationship between applied force, friction, and the resulting state of motion (acceleration vs. uniform velocity).

Statement-wise Analysis

Statement 1 is Incorrect. According to Newton's First Law of Motion (Law of Inertia), an object in motion will continue moving at the same speed unless acted upon by an external unbalanced force. When pedalling stops, the bicycle slows down not merely because the pedalling force is absent, but because of the presence of retarding forces such as friction (between the tyres and the road) and air resistance. If these opposing forces were absent, the bicycle would continue moving perpetually even without pedalling.
Statement 2 is Correct. To move an object at a uniform velocity, the net force acting on it must be zero (since acceleration is zero). This requires the applied force (pedalling) to exactly balance the opposing frictional force. In this state of equilibrium, the forces cancel each other out, maintaining constant speed.
Statement 3 is Incorrect. If the pushing force is greater than the frictional force, there is a net unbalanced force acting in the direction of motion. According to Newton's Second Law ($F = ma$), a net force produces acceleration. Consequently, the velocity of the object would increase, and it would not move with a uniform velocity.

Key Takeaway: Uniform velocity implies zero acceleration, which occurs only when the net force on an object is zero. This happens when the driving force is exactly equal and opposite to the resistive forces (friction).

Your note

More from Chapter 2: Force and laws of motion

With reference to the property of inertia, which one of the following comparisons is correct?

easy

The phenomenon of gun recoil is a direct consequence of:

easy

A motor vehicle with a dead battery requires a continuous push to start rather than a sudden jerk. This is best explained by the fact that:

medium

Consider the following everyday experiences: 1. Dust coming out of a carpet when beaten with a stick. 2. Leaves getting detached from a tree when shaken vigorously is unrelated to the property of inertia. 3. A coin falling into a tumbler when the card below it is flicked. Which of the above can be explained by the Law of Inertia?

medium

With reference to Newton's Third Law, action and reaction forces act:

medium

Keep practising Chapter 2: Force and laws of motion

Work through every question from this NCERT chapter.

Browse all NCERT Class 9 Science chapters