Q4. Answer the following question in one sentence.
- What is the SI unit of mass?
Answer. The SI unit of mass is the kilogram (kg).
- Give one example of oscillatory Motion.
Answer. An example of oscillatory motion is the swinging of a pendulum.
- Convert 4 km into meters.
Answer. To convert 4 kilometres into meters, multiply by 1,000: 4 kilometers is equal to 4,000 meters.
D. Which type of motion is seen in the drill machine?
Answer.
Q5. Answer the following in questions in 2-3 sentences.
- What is random motion?
Answer. Random motion refers to particles’ unpredictable and erratic movement in all directions. This type of motion does not follow a specific path or pattern and is commonly observed in gases and liquids, such as the movement of dust particles in the air or the motion of pollen grains in water.
- Explain with the help of an example when an object has rectilinear motion.
Answer. Rectilinear motion occurs when an object moves along a straight line. For example, a car driving on a straight road or a ball being thrown directly upward exhibits rectilinear motion, as the path of the object does not curve or change direction.
C. Explain the term physical quantity.
Answer. A physical quantity is a characteristic of a material or system that can be measured and quantified. Examples include length, mass, time, and temperature, which are all expressed with specific units to provide meaningful information about the physical world.
D. What is the length?
Answer. Length is the measurement of the extent of an object from one end to the other along its longest dimension. It is a fundamental physical quantity used to determine the size or distance between two points and is commonly measured in units such as meters, centimetres, or inches.
- While measuring the length of a knitting needle, the reading of the scale at one end is 3.0 cm at the other end is 33.1 cm. What is the length of the needle?
Answer. To find the length of the knitting needle, subtract the reading at one end from the reading at the other end:
Length of the needle = Reading at the end – Reading at the start
= 33.1 cm – 3.0 cm
= 30.1 cm
Therefore, the length of the knitting needle is 30.1 cm.
6. Give a reason.
a. The movement of the pendulum of a clock is an example of periodic motion.
Answer. The movement of the pendulum of a clock is an example of periodic motion because it swings back and forth in a regular and repeating pattern. This consistent motion allows clocks to keep accurate time by marking equal intervals with each swing.
b. Why is footstep not considered as standard unit?
Answer. A footstep is not considered a standard unit because it lacks uniformity and precision. Unlike standardized units such as meters or inches, the length of a footstep can vary greatly between individuals and is not consistent for accurate measurement or scientific purposes.
- Rest and motion are relative terms?
Answer. Rest and motion are relative because they depend on the observer’s frame of reference, changing based on the observer’s movement.
7. Answer the following in 4-5 sentences.
a. Seema measured the length of her book and noted it as 25 CMS. What is the mistake in her observation? Suggest what would be the correct observation.
Answer. Seema’s observation of 25 CMS is incorrect because “CMS” should be “cm” for centimeters. The correct observation should be 25 cm.
b. Give an example of one similarity and one difference between two objects based on the type of motion.
Answer. Both a car and a pendulum can move (similarity), but a car moves linearly while a pendulum swings back and forth (difference).
C. When can we say that an object has translatory motion? State the different types of translatory motion
Answer. An object has translatory motion when all its parts move the same distance in the same time.There are two types: rectilinear (straight path) and curvilinear (curved path).