Velocity and Acceleration

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1. CSCA Physics December 2025 Past Paper
   As shown in the figure, an object moves from point $A$ through point $B$ to point $C$ along two semicircles with radius $R = 6 \mathrm {~m}$, taking a time of $t = 4 \mathrm {~s}$. The magnitude of its average velocity is ().
   • A．$6 \mathrm {~m} / \mathrm { s }$
   • B．$12 \mathrm {~m} / \mathrm { s }$
   • C．$6 \pi \mathrm {~m} / \mathrm { s }$
   • D．$3 \pi \mathrm {~m} / \mathrm { s }$
   ดูคำตอบและวิธีทำ

   คำตอบ: A

   1 Displacement is the straight line from A to C. The two semicircles each have diameter $2 R = 12 \mathrm {~m}$, so the displacement is $x = 4 R = 24 \mathrm {~m}$. 2 Average velocity $= x / t = 24 \mathrm {~m} / 4 \mathrm {~s} = 6 \mathrm {~m} / \mathrm { s }$, option A. 3 Note: the path length is $2 \pi R = 12 \pi \mathrm {~m}$, so $3 \pi \mathrm {~m} / \mathrm { s }$ (option D) is the average speed, not the average velocity.
   ดูในชุดข้อสอบเต็ม CSCA Physics December 2025 Past Paper
2. CSCA Physics March 2026 Past Paper
   The x-t graph for a toy car in linear motion is shown. Which statement is correct?
   • A．Displacement from $0 - 4 \mathrm {~s}$ is 8 m
   • B．Velocity from $0 - 4 \mathrm {~s}$ is $1.0 \mathrm {~m} / \mathrm { s }$
   • C．Average velocity from $0 - 5 \mathrm {~s}$ is $0.8 \mathrm {~m} / \mathrm { s }$
   • D．Velocity from $4 - 5 \mathrm {~s}$ is $0.8 \mathrm {~m} / \mathrm { s }$
   ดูคำตอบและวิธีทำ

   คำตอบ: B

   From graph: $0 - 4 \mathrm {~s} , x$ goes from 0 to 4 m linearly. A: displacement is 4 m , not 8 . $B : v = 4 / 4 = 1.0 \mathrm {~m} / \mathrm { s }$, correct. C: at 5 s position returns to 0 , average velocity $= 0 / 5 = 0$. D: $4 - 5 \mathrm {~s}$, displacement $= 4 \mathrm {~m}$ in 1 s , speed $= 4 \mathrm {~m} / \mathrm { s }$. Answer: B.
   ทำข้อสอบเต็มชุด CSCA Physics March 2026 Past Paper — จับเวลาและให้คะแนน
3. CSCA Physics April 2026 Past Paper
   As shown in the figure, an object travels along a path consisting of two semicircles end-to-end (each of radius 4 m ) from $A$ through $B$ to $C$. Points $A , B , C$ are collinear along the east-west direction. The travel takes 2 s . The magnitude of the average velocity is
   • A．$4 \mathrm {~m} / \mathrm { s }$
   • B．$0 \mathrm {~m} / \mathrm { s }$
   • C．$2 \mathrm {~m} / \mathrm { s }$
   • D．$8 \mathrm {~m} / \mathrm { s }$
   ดูคำตอบและวิธีทำ

   คำตอบ: D

   Each semicircle has diameter $2 R = 8 \mathrm {~m}$, so $| A B | = | B C | = 8 \mathrm {~m}$. Because $A$, $B , C$ are collinear, the total displacement is $| A C | = 16 \mathrm {~m}$. Average velocity $= \frac { | A C | } { t } = \frac { 16 } { 2 } = 8 \mathrm {~m} / \mathrm { s }$.
   ทำข้อสอบเต็มชุด CSCA Physics April 2026 Past Paper — จับเวลาและให้คะแนน