Assertion and Reason: Motion and Measurement of Distances | Class 6: Additional Practice PDF Download

The questions below consists of an assertion and a Reason. Use the key to choose the appropriate answer. 
Q1: Assertion: For the measurements unit international system of units are the system or method used.
Reason: The kg is the SI unit of length.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Ans: (c)
In this question, both the assertion and the reason are incorrect statements. The assertion states that the international system of units (SI) is used for measurement, which is true. However, the reason given is incorrect. The kilogram (kg) is not the SI unit of length; it is the unit of mass. The SI unit of length is the meter (m). Therefore, both the assertion and the reason are incorrect, and the correct answer is option C.

Q2: Assertion: The objects which are move along a straight line are called rectilinear motion.
Reason: The objects which are move in a circular form are called circular  motion of that object.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Ans: (b)
 In this question, the assertion is a correct statement. Rectilinear motion refers to the motion of objects moving in a straight line. However, the reason provided is incorrect. Circular motion refers to the motion of objects moving in a circular path, not in a straight line. Therefore, the assertion is correct, but the reason is incorrect, leading to option B as the correct answer.

Q3: Assertion: For measuring the length of an object choose a suitable device.
Reason: We can measure the length of a curved line directly by using a meter scale.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Ans: (c) 
In this question, the assertion is a correct statement. When measuring the length of an object, it is important to choose a suitable measuring device to ensure accurate results. However, the reason given is incorrect. A meter scale is a straight measuring device and cannot be used to measure curved lines directly. Curved lines need specialized tools like a flexible measuring tape or other methods like using a piece of string to trace the curve and then measuring the string. Therefore, the assertion is correct, but the reason is incorrect, leading to option C as the correct answer.

Q4: Assertion: A branch of a tree moving to and Fro motion of a child on a swing strings of a guitar are the example of periodic motion.
Reason: The motion in which an object repeats it’s motion after some times known as periodic motion
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Ans: (c)
In this question, both the assertion and the reason are correct statements. The assertion lists examples of periodic motion, where certain objects exhibit repetitive back-and-forth motion. The reason accurately defines periodic motion as the type of motion in which an object repeats its motion pattern after a certain time interval. Since both the assertion and the reason are correct and the reason explains the assertion accurately, the correct answer is option A.

Q5: Assertion: The motion of a child on a swing is an example of periodic motion.
Reason: Periodic motion is one that repeats itself after regular intervals of time.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Ans: (a)
The motion of a child on a swing repeats itself after regular intervals of time, hence it is a periodic motion.

Q6: Assertion: The speed of an object is the distance covered per unit time.
Reason: Speed is a scalar quantity.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Ans: (b)
While both statements are true, the reason does not explain why speed is defined as the distance covered per unit time.

Q7: Assertion: The SI unit of speed is meter per second.
Reason: The SI unit of distance is meter and that of time is second.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Ans: (a)
Speed is the distance covered per unit time, hence its SI unit is derived from the units of distance and time, which are meter and second respectively.

Q8: Assertion: A car moving on a straight road is an example of rectilinear motion.
Reason: Rectilinear motion is the motion of an object along a straight line.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Ans: (a)
A car moving on a straight road is moving in a straight line, hence it is an example of rectilinear motion.

Q9: Assertion: A body in motion always covers equal distances in equal intervals of time.
Reason: The speed of a body is constant.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Ans: (d)
A body in motion does not always cover equal distances in equal intervals of time. It only happens when the body is moving at a constant speed. The speed of a body can be constant, but it's not a rule. It can change due to various factors like gravity, friction, applied force, etc.