Important Questions Test: Motion & Measurement of Distances - UPSC MCQ

A swing moves back and forth in a regular, repeating pattern, which is characteristic of periodic motion. This type of motion repeats at regular intervals, such as the swinging of a pendulum.

• A: Rectilinear motion refers to motion along a straight line, which is not the case for a swing.
• B: Rotational motion refers to motion around a fixed axis, like a spinning wheel, not the type of motion a swing exhibits.
• D: Circular motion refers to motion along a circular path, but a swing typically moves in a back-and-forth arc, not a full circle.

Thus, a moving swing exhibits periodic motion.

Topic in NCERT: TYPES OF MOTION

Line in NCERT: "A branch of a tree moving to and fro, motion of a child on a swing, strings of a guitar or the membrane of drums (tabla) being played, are all examples of periodic motion where an object or a part of it repeats its motion after a fixed interval of time."

 When a bullet is fired from a gun, it typically moves in a straight line in the direction of the force applied by the gunpowder's explosion. This is known as rectilinear motion, which refers to motion along a straight path.

• A: Non-periodic motion refers to motion that does not repeat at regular intervals, which could describe some random or irregular movements, but the bullet's motion is more specific.
• C: Random motion refers to motion without a definite pattern or direction, which does not apply to a bullet's path.
• D: Circulatory motion is not a term used in the context of a bullet's movement, as a bullet moves in a straight line, not in a circular path.

Therefore, the bullet exhibits rectilinear motion.

Topic in NCERT: TYPES OF MOTION

Line in NCERT: "In all these examples we see that the objects move along a straight line. This type of motion is called rectilinear motion."

The least count of a measuring instrument is the smallest change in the quantity being measured that can be detected. In this case, the scale has 20 divisions in 1 centimeter. To find the least count, we divide the smallest division (1 cm) by the number of divisions.

So, the least count is 0.05 cm or
0.5 mm as 1 cm =10mm so 0.05cm = 0.5mm . Therefore, the correct answer is (d) 0.5 mm.

• 100 millimeters (mm) is equal to 10 centimeters (cm) because 1 cm = 10 mm. 

Let's verify the other options:

• A: 10 dm is incorrect because 1 dm (decimeter) = 100 mm, not 100 mm = 10 dm.
• B: 100 dm is incorrect because 100 millimeters is much smaller than 100 decimeters.
• C: 1 m is incorrect because 1 meter = 1000 mm, not 100 mm.

Thus, 100 mm = 10 cm is the correct answer.

Topic in NCERT: Units of Measurement

Line in NCERT: "Each metre (m) is divided into 100 equal divisions, called centimetre (cm)."

One meter is equal to 100 cm and one cm is equal to 10 mm. therefore, a meter is equal to 100 × 10 = 1000 mm.

Topic in NCERT: Units of Measurement

Line in NCERT: "Each metre (m) is divided into 100 equal divisions, called centimetre (cm). Each centimetre has ten equal divisions, called millimetre (mm)."

The motion of an object that repeats itself after regular intervals of time is called periodic motion.
The motion of simple pendulum is an example of periodic motion.

Topic in NCERT: TYPES OF MOTION

Line in NCERT: "In some cases, an object repeats its motion after some time. This type of motion is called periodic motion."

• Meter, Feet, and Kilometer are units of distance.
• Kilogram is a unit of mass.

Topic in NCERT: SI Units and Measurement

Line in NCERT: "The SI unit of length is a metre."

1 centimeter is equal to 10 millimeters.
Therefore, the correct answer is (c) 10 mm.

Topic in NCERT: UNITS OF MEASUREMENT

Line in NCERT: "1 cm = 10 mm"

Measurement is the process of comparing an unknown quantity with a known or standard quantity.
Therefore, the correct answer is (a) Measurement.

Topic in NCERT: MOTION AND MEASUREMENT OF DISTANCES

Line in NCERT: "We see that, measurement means the comparison of an unknown quantity with some known quantity."

The blades of a fan move in a circular path as they rotate around the axis of the fan. This type of motion is called circular motion.

Let's review the other options:

• B: Non-periodic motion is incorrect because the fan blades rotate in a regular, repeating manner, making the motion periodic.
• C: Rectilinear motion refers to motion along a straight line, which doesn't describe the movement of fan blades.
• D: All of these is incorrect because circular motion is the most accurate description of the fan blades' movement.

Thus, the correct answer is circular motion.