Chapter–3: Motion in a Straight Line Assertion Reason
These questions of two statements each, printed as Assertion and Reason. While answering these Questions you are required to choose any one of the following four responses.
(A) If both Assertion & Reason are true & the Reason is a correct explanation of the Assertion.
(B) If both Assertion and Reason are true but Reason is not a correct explanation of the Assertion.
(C) If Assertion is true but the Reason is false.
(D) If Assertion & Reason both are false.
Assertion-Reason Questions: Chapter 3 – Motion in a Straight Line
Assertion: Displacement is a vector quantity.
Reason: Displacement has both magnitude and direction.
False
Answer: True. Displacement is indeed a vector quantity as it involves both magnitude and direction.
Assertion: Velocity can be negative.
Reason: Negative velocity indicates motion in the opposite direction to the positive axis.
False
Answer: True. Velocity is a vector quantity that can have negative values indicating motion in the opposite direction.
Assertion: Acceleration is always positive when an object is speeding up.
Reason: Acceleration is the rate of change of velocity with respect to time.
False
Answer: False. Acceleration can be negative when an object is slowing down, indicating a change in velocity in the opposite direction to its motion.
Assertion: Distance traveled by an object is always greater than or equal to its displacement.
Reason: Distance is a scalar quantity that measures the length of the actual path traveled by an object.
False
Answer: True. Distance traveled by an object is always equal to or greater than its displacement because it accounts for the total path length, which can include changes in direction.
Assertion: Instantaneous velocity of an object is defined as the limit of the average velocity as the time interval approaches zero.
Reason: Instantaneous velocity gives the velocity of an object at a particular instant of time.
False
Answer: True. Instantaneous velocity is indeed defined as the limit of the average velocity as the time interval approaches zero, providing the velocity at an exact moment.
Assertion: Uniform motion is characterized by constant acceleration.
Reason: In uniform motion, velocity remains constant over time.
False
Answer: False. Uniform motion is characterized by constant velocity, not necessarily constant acceleration.
Assertion: Negative acceleration always implies retardation.
Reason: Negative acceleration means the object is slowing down.
False
Answer: True. Negative acceleration indicates a decrease in velocity, or retardation, of the object.
Assertion: A body moving in a circular path with constant speed has zero acceleration.
Reason: Acceleration is defined as the rate of change of speed of the body.
False
Answer: False. Although the speed may be constant, the direction of motion changes continuously, leading to a non-zero acceleration (centripetal acceleration).
Assertion: A body in free fall near the surface of the Earth experiences constant acceleration.
Reason: Acceleration due to gravity near the Earth’s surface is constant.
False
Answer: True. The acceleration due to gravity (g) near Earth’s surface is approximately constant (9.8 m/s²), leading to a constant acceleration for objects in free fall.
Assertion: The area under the velocity-time graph represents the displacement of an object.
Reason: Velocity is the rate of change of displacement with respect to time.
False
Answer: True. The area under the velocity-time graph gives the displacement because velocity-time graph is instantaneous velocità
Chapter–2: Units and Measurements Assertion Reason
Chapter–4: Motion in a Plane Assertion Reason