IBDP Physics- A.1 Kinematics- IB Style Questions For SL Paper 1A -FA 2025
▶️ Answer/Explanation
1. Define Velocity:
Velocity is a vector quantity. It is defined as the rate of change of displacement (or position) with respect to time.
2. Distinguish Instantaneous vs Average:
Average velocity is total displacement over total time. Instantaneous velocity is the limit of this ratio as the time interval approaches zero, i.e., the derivative of position with respect to time.
3. Evaluate Options:
- (A) Displacement / time taken = Average Velocity.
- (B) Rate of change of position = Instantaneous Velocity (\(v = \frac{ds}{dt}\)).
- (C) Distance / time = Average Speed.
- (D) Rate of change of distance = Instantaneous Speed.
✅ Answer: (B)
▶️ Answer/Explanation
Initially, the net force on the block is
\(F_{\text{net,1}} = ma = 2.0 \times 1.0 = 2.0\,\mathrm{N}\).
With an applied force of \(4.0\,\mathrm{N}\), the resistive force is
\(R = 4.0 – 2.0 = 2.0\,\mathrm{N}\).
When the applied force is doubled, \(F_2 = 8.0\,\mathrm{N}\) and the resistive force remains \(2.0\,\mathrm{N}\).
So the new net force is
\(F_{\text{net,2}} = 8.0 – 2.0 = 6.0\,\mathrm{N}\).
Hence the new acceleration is
\(a_2 = \dfrac{F_{\text{net,2}}}{m} = \dfrac{6.0}{2.0} = 3.0\,\mathrm{m\,s^{-2}}\).
✅ Answer: (B)
▶️ Answer/Explanation
The displacement from \(X\) to \(Y\) is the straight-line distance (the chord), not the distance travelled along the track.
From the diagram, \(X\) and \(Y\) are \(90^\circ\) apart around the circle, so the radii to \(X\) and \(Y\) are perpendicular. This forms a right-angled triangle with legs \(R\) and \(R\).
Therefore, the displacement magnitude is
\(XY = \sqrt{R^2 + R^2} = R\sqrt{2}\).
✅ Answer: (C)