Question

The speed-time graph below shows a non-stop service of the Very Slow train travelling from Bangkok to Chiang Mai.
Find;
a) the acceleration of the train at the start of the journey?
b) the deceleration of the train at the end of the journey?

Leave answers to nearest whole number where necessary.

Answer 1

Answer:

a) (70 - 0) km/h ÷ 1 hour

= 70 km/h²

b) (0 - 70) km/h ÷ (8.5 - 7.5) hours

= -70 km/h²

Explanation:

a) The final speed of the train is 70 km/h. The initial speed of the train is 0 km/h. The time to accelerate to a constant speed is 1 hour. Subtract the initial speed from the final speed to get the constant speed of the train. Divide the constant speed of the train with the time to accelerate to a constant speed.

=> (Final speed - Initial speed) ÷ The time to accelerate to a constant speed

=> (70 - 0) ÷ 1

=> 70÷1

=> 70 km/h²

b) The final speed of the train is 0 km/h. The initial speed of the train is 70 km/h. The time to decelerate to a constant speed is 7.5 hours. Subtract the initial speed from the final speed to get the deceleration. Then subtract the time when the deceleration started from the time when the deceleration ended to get the time to decelerate from the constant speed. Divide the deceleration with the time to decelerate from the constant speed.

=> (Final speed - Initial speed) ÷ (Time when deceleration ended - Time when deceleration started)

=> (0 - 70) ÷ (8.5 - 7.5)

=> -70 ÷ 1

=> -70 km/h²

I hope it was helpful. <3