NEETPhysicsMotion in One Dimension
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): For a ball thrown vertically upwards and returning to the ground, its acceleration is constant and directed downwards throughout the motion. Reason (R): The speed-time graph for the entire journey of this ball is a straight line that crosses the time axis. In the light of the above statements, choo
Options
- ABoth (A) and (R) are true and (R) is the correct explanation of (A)
- BBoth (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
Correct answer
C. (A) is true but (R) is false
Step-by-step solution
Assertion (A) is true because a ball thrown vertically upwards moves under the influence of gravity alone (ignoring air resistance), so it experiences a constant downward acceleration ( g ) throughout its upward and downward journey. Reason (R) is false because speed is a scalar quantity and is the magnitude of velocity. Therefore, speed can never be negative. The speed-time graph of a ball thrown upwards will decrease linearly to zero at the highest point and then increase linearly as it falls back, forming a V-sh