9th Physics Chapter1 Physical Quantities and Measurement

1. Explain the significance of the coefficient in scientific notation.

The coefficient in scientific notation represents the significant digits of a number, providing the essential numerical information.

 

When is it appropriate to use scientific notation in physics calculations?

Scientific notation is often used in physics calculations when dealing with very large or very small measurements, such as distances in space or particle sizes.

2. Describe the proper technique for using a stopwatch to measure time accurately.

Start the stopwatch when the event begins and stop it precisely when the event ends. Avoid parallax error by ensuring that you view the stopwatch directly from the front.

 

Explain the correct method for reading the volume from a measuring cylinder.

Read the volume at the bottom of the meniscus, which is the curved surface of the liquid. Ensure that the cylinder is on a flat surface and eye level with the liquid level.

 

3. What is a physical quantity, and how does it differ from a scalar quantity?

A physical quantity is a characteristic that can be measured. Scalars have only magnitude, while vectors have both magnitude and direction.

Differentiate between precision and accuracy in measurements, providing examples.

Accuracy refers to how close a measurement is to the true value, while precision is the degree of consistency in repeated measurements. An accurate and precise measurement hits the target consistently, while inaccurate but precise measurements cluster around a common value.

 

4. Explain the principle of operation of a screw gauge.

A screw gauge measures the dimensions of an object by translating the linear motion of a screw into rotational motion. The movement of the screw advances a spindle, allowing precise measurements to be made.

 

How is the least count of a screw gauge calculated?

The least count (LC) is calculated by dividing the pitch of the screw by the total number of divisions on the circular scale. Mathematically, LC = Pitch / Total number of divisions.

 

5. Explain the principle of operation of a lever balance in measuring mass.

A lever balance operates based on the principle of a lever. The mass to be measured is placed on one side, and standard masses are added to the other side until equilibrium is achieved.

 

Explain the working principle of an electronic balance.

An electronic balance works by measuring the force exerted by an object due to gravity. The force is converted into an electrical signal, which is then used to determine the mass of the object.