物理位置與運動 DSE、CE 選擇題（第 2 頁）

11.

Questions 1 and 2 : Patrick is driving along a straight horizontal road. At time $t = 0$ , he observes that an accident has happened. He then applies the brakes to stop his car with uniform deceleration. The graph shows the variation of the speed of the car with time.

Speed-time graph: constant 14 m/s until 0.8 s, then decreasing linearly to zero at 5.0 s

What is the reaction time of Patrick ?

12.

Questions 1 and 2 : Patrick is driving along a straight horizontal road. At time $t = 0$ , he observes that an accident has happened. He then applies the brakes to stop his car with uniform deceleration. The graph shows the variation of the speed of the car with time.

Find the distance travelled by the car from time $t = 0$ to $5.0$ s.

13.

Velocity-time graphs of P (steep line stopping at a constant value) and Q (straight line of smaller slope) from the origin, with t1 and t2 marked

The figure shows the velocity-time graphs of two students $P$ and $Q$ running along a straight road. They start at the same point. Which of the following statements is/are correct ?

(1)The average speed of

P

between

t = 0

and

t = t_1

is larger than that of

Q

.

(2)At

t = t_1

,

P

and

Q

reach the same point.

(3)At

t = t_2

,

Q

is ahead of

P

.

14.

Questions 1 and 2 : The figure shows the velocity-time graph of a car travelling along a straight road.

Velocity-time graph with the area between the graph and the time axis shaded from t = 0 to t1, then negative velocity from t1 to t2

What physical quantity does the area of the shaded region represent ?

15.

Questions 1 and 2 : The figure shows the velocity-time graph of a car travelling along a straight road.

Which of the statements are correct ?

(1)The car changes its direction of travel at

t = t_1

.

(2)The car is farthest away from the starting point at

t = t_1

.

(3)The car returns to its starting point at

t = t_2

.

16.

A car starts at point $A$ and travels along a circular path of radius $30$ m. After $15$ s, the car returns to point $A$ . Find the average speed of the car within this period of time.

Circular path of radius 30 m starting and ending at point A

17.

A plane starts from rest and accelerates at $2$ m s $^{-2}$ . If the minimum take-off speed is $60$ m s $^{-1}$ , find the minimum distance travelled by the plane before it takes off.

18.

Distance-time graphs of cars P and Q meeting at t = 5 s, both reaching about 20 m

The figure above shows the distance-time graphs of two toy cars $P$ and $Q$ moving along a linear track. Which of the following statements is/are correct ?

(1)Car

P

will reach the

20

m-mark first.

(2)Car

P

is overtaking car

Q

at

t = 5

s.

(3)The average speed of car

P

in the first

5

s is smaller than that of car

Q

.

19.

A piece of stone is hung from a balloon, which is rising vertically upward. If the string connecting the stone and the balloon suddenly breaks, which of the following velocity-time graphs represents the subsequent motion of the stone ? (Note : Velocity pointing upward is taken to be positive.)

20.

Graph of distance from P against time: straight line decreasing from a positive value to zero

A car travels along a straight road. The variation of the distance of the car from a fixed point $P$ on the road with time is shown above. Which of the following statements is correct ?