Published on Apr 02, 2024
For wood to be pulled along a surface, the amount of force needed to get it moving must be greater than the total forces that are preventing it from moving.e.g. Friction. I will Test what force is needed to pull the block along at a steady speed and what effect changing the mass of the object will have. This force will be measured in Newtons (N).
An effect, which may change the force needed to pull the block and masses along, is Friction. Friction is caused by microscopic ‘bumps’ on the surfaces of the two objects. These ‘bumps’ run into each other when the two surfaces rub together or along each other. These collisions prevent the objects moving past each other smoothly, which means that more force is needed to keep the object moving at a steady speed.
To establish relationship between weight of a rectangular wooden block lying on a horizontal table and the minimum force required to just move it using a spring balance.
According to Newton’s Second Law of Motion, the force acting on a body is directly proportional to the product of the mass of the body and the acceleration produced in the body by the application of the force. The acceleration takes place in the direction in which the force acts.
Newton’s Second Law of Motion precisely explains the relationship between force and acceleration.
Suppose a body of mass ‘m’ is moving by the application of a force ‘F’, then the produced acceleration ‘a’ will be directly proportional to the applied force.
Acceleration ∝ Force
F ∝ a
F ∝ m
Therefore, F = kma ………… (1)
Where k is constant of proportionality
In SI unit, k =1
Therefore, F = ma
Importance of the Newton’s Second Law of Motion
• Newton’s Second Law of Motion gives a quantitative measure of force.
F = ma
• The Second Law is a basic law of motion because both First and Third Law can be derived from this law.
Examples of the application of the Second Law of Motion
1. Breaking a slab of ice.
2. Catching a cricket ball.
3. An athlete practicing high jump or long jump.
From these examples, it is clear that we unknowingly try to reduce or increase the rate of change of momentum, by reducing or increasing the time period in which this change in momentum takes place.
Wooden block and spring balance of 5 N.
1. A wooden block with a hook is placed on a table.
2. Note down the least count of the spring balance.
3. The spring balance is attached to the hook.
4. Hold the spring in such a way that the reading displayed in the spring balance can be noted down without any parallax error.
5. The applied force on the spring balance is gradually increased until it just starts to move.
6. The reading of the spring balance is noted.
Least count of the spring balance = value of 1 small division = …….g.wt
Force applied to just move the block is directly proportional to the mass of the block.
ie, F ∝ M
1. A suitable spring balance to pull the block must be used.
2. The spring balance should be brought in elastic mode before doing the experiment.
3. The reading of the spring balance should be taken without any parallax error.
4. A smooth table or surface must be used.
• Manual of Secondary Science Kit for Classes IX and X - Published by NCERT
• Science textbook for class IX – Published by National Council of Educational Research and Training, New Delhi
• New Living Science PHYSICS for CLASS 9 With More Numerical Problems - Dhiren M Doshi
• Longman science Physics 9 - Singh Sardar
