Chapter: Mechanics
A 5 N force is defined when a mass of 10 kg isaccelerated with
The governing principle is Newton's Second Law of Motion, expressed as:
Where:
F = Force (in Newtons, N)
m = Mass (in kilograms, kg)
a = Acceleration (in meters per second squared, m/s2)
Given:
F = 5 N
m = 10 kg
Using the formula:
Rearranging gives:
- Option (a): 5.0 cm/s2 = 0.05 m/s2 (Incorrect)
- Option (c): 0.5 cm/s2 = 0.005 m/s2 (Incorrect)
- Option (d): 5.0 m/s2 (Incorrect)
Remember: F = ma is key. Force and acceleration are directly proportional.
A force diagram showing a 10 kg mass with an arrow indicating a 5 N force applied horizontally, leading to an acceleration vector pointing in the same direction with magnitude 0.5 m/s2.
Verified against NCERT Class IX Physics, Chapter 9 (Force and Laws of Motion).
Weight and mass of an object are defined with Newtons laws of motion. Which among the following is true?
According to Newton's laws of motion, weight \( W \) is the gravitational force acting on an object, related to its mass \( m \) by the equation:
Where:
Mass is defined as the measure of the amount of matter in an object. It remains constant regardless of location, thereby acting as a constant of proportionality in the weight equation. Weight, on the other hand, is variable - it depends on gravitational force, which changes with the distance from the center of the Earth and the local gravitational field strength.
To illustrate:
Option (a) incorrectly states that weight is a constant of proportionality. Option (c) is false since mass is indeed a constant of proportionality. Option (d) mistakenly labels weight as a universal constant; however, it varies with gravitational force.
Remember: "Mass is Matter's Measure, Weight Wavers with Gravity."
A diagram illustrating the relationship between mass and weight, showing a scale with mass on one side and weight measurement on the other, emphasizing that while mass remains consistent, weight fluctuates with different gravitational forces.
Verified against NCERT Class IX Physics, Chapter 4 (Force and Motion)
Why a fielder in the ground gradually pulls his hands backward while catching a fast moving cricket ball?
The principle relevant here is the impulse-momentum theorem, which states:
Impulse is the product of the average force and the time duration over which the force acts.
When a fielder catches a cricket ball, he effectively receives momentum from the ball, which is equal to:
where \( m \) is the mass of the ball (in kg) and \( v \) is its velocity (in m/s).
By pulling his hands backward, the fielder increases the time (\( \Delta t \)) over which the ball decelerates to rest. This longer time reduces the average force (\( F \)) experienced, calculated as:
Rearranging gives:
This indicates that increasing \( \Delta t \) (catching time) reduces force \( F \), mitigating injury and improving catching success.
Remember: More Time = Less Force when catching. This mnemonic highlights the benefit of time during collisions.
A diagram depicting a fielder catching a ball, showing forces acting on the ball and a timeline indicating increased catching time through a backward motion of hands.
Verified against NCERT Class XI Physics, Chapter 5 (Laws of Motion).
Which one of the following statements for second law of motion is NOT correct?
Newton's Second Law of Motion is succinctly described by the relation:
Here, \( F \) is the net force, \( p \) is momentum, and \( t \) is time.
According to Newton's Second Law, force is directly proportional to the rate of change of momentum:
where \( m \) is the mass and \( a \) is the acceleration. Thus, the correct interpretation is that \( F \) relates to \( \frac{dp}{dt} \), not simply \( p \).
Identifying the incorrect statement reveals that momentum \( p = mv \) is not a direct factor in this relationship, hence disproving Option D.
Remember: \( F \propto \frac{dp}{dt} \) highlights the relationship between force and momentum change.
A diagram showing a force vector acting on an object with a visible acceleration vector illustrates the proportional relationships defined by Newton's Second Law. This should depict the direction of force and acceleration clearly.
Verified against NCERT Class XI Physics, Chapter 5 (Laws of Motion).
A car has an initial velocity of 12 m/s and is brought to rest over a distance of 45 m. The acceleration of the car is.
Option C is correct. The acceleration of the car is negative, indicating deceleration.
Acceleration is the rate of change of velocity; negative acceleration denotes deceleration.
To quickly find acceleration when an object is brought to rest, use \(v^2 = u^2 + 2as\).
Deceleration implies negative acceleration, calculated via \(a = -\frac{u^2}{2s}\) formula.
This is a preview of the SenaPrep Question Bank. To access comprehensive chapter-wise exercises, bookmark questions, attempt custom tests, and track your progress, download the official SenaPrep Android App.
Download Android App
SENAPREP