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  1. You have some information missing. How much does its velocity decrease? As far as I remember this question, the velocity should decrease from 30 m/s to 20 m/s in 100 m. So, I will use this to do the question. Initial velocity, u = 30 m/s Final...

  2. Answer : E 任何物件於地球表面,都受到gravitational force (g) ge 影響。Gravitation force會向住地心 (earth core) 拉住件物件。 而你亦都應該學左 Gravitation force = mg 所有物件都有一個Gravitation force (mg) 向下拉 如果該物件係置於地面上...

  3. Let d be the distance between A and B hence time t1 to travel from A to B = distance/speed = d/1 = d time t2 to travel from B to A = d/2 Total distance travelled in the whole journey = 2d total time taken = t1 + t2 = d + d/2 = 3d/2 Therefore, average...

  4. s=ut+(1/2)at2 if t=1, s=0+(1/2)(10)(1)2 s=5 m if t=2, s=0+(1/2)(10)(2)2 s=20 m if t=3, s=0+(1/2)(10)(3)2 s=45 m 45 m係指該物件由t=0到t=3期間所行走的distance/displacement 0 s to 1 s is the first second 1.01 s to 2 s is the second second(第二秒) 2.01 s to 3 s is...

  5. First of all, after 20 minutes, the car has travelled 60 x (20/60) = 20 km. So at that time the car still has to travel 40km. If the car travels at 80 km/h for the remaining distance, it needs a further 40/80 = 0.5 hours or 30...

  6. Initial velocity, u = 50 km/h = 50 / 3.6 = 13.89 m/s Final velocity, v = 0 Stopping distance, s = 15 m By equation of motion, v2 = u2 - 2as 0 = (13.89)2 - 2a(15) Deceleration, a = 6.43 ms-2 Now, initial velocity, u = 70 km/h = 70/3.6 = 19.44 m/s By equation of motion, v2 = u2...

  7. (a) Distance covered by satellite in one revolution round the earth = 2 x pi x (350+6370) km where pi = 3.14159..... Hence, average speed = distance/time = 2 x pi x (350+6370) /1.5 km/h (b) Similar, distance covered by satellite in one revolution = 2 x pi x (h+ 6370) km where h (in km) is the...

  8. Time needed for reaching the MAXIMUM velocity : u=0, v=10ms^-1, a=3.3ms^-2, By v=u+at,10=0+3.3t t=10/3.3 s distance of the runner's velocity change from 0 to 10ms^-1 : By v^2-u^2=2aS, 10^2-0=2(3.3)S S=100/6...

  9. 你不可以這樣計,因為你無法得知個Ball是在何時何地開始Fall freely from rest,也無法得知個Ball在Point A的速度 但你在Sub數時,已假設個Ball是在Point A fall freely from rest,也就是事先假設個Ball在...

  10. A man standing in a stationary lift releases a stone. The stone takes t seconds to reach the floor of the lift. If the lift is moving downwards with constant velocity instead of being stationary A.The stone...