A train moving at a speed of 72 km/h applies brakes and comes to a stop in 5 sec

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Question: A train moving at a speed of 72 km/h applies brakes and comes to a stop in 5 seconds. What is the acceleration of the train?

Options:

Correct Answer: -4 m/s²

Solution:

First, convert speed to m/s: 72 km/h = 20 m/s. Using a = (v - u)/t = (0 - 20)/5 = -4 m/s².

A train moving at a speed of 72 km/h applies brakes and comes to a stop in 5 seconds. What is the acceleration of the train?

A train moving at a speed of 72 km/h applies brakes and comes to a stop in 5 seconds. What is the acceleration of the train?

Step 1: Convert the speed of the train from kilometers per hour (km/h) to meters per second (m/s). Use the conversion factor: 1 km/h = 1/3.6 m/s. So, 72 km/h = 72 / 3.6 = 20 m/s.
Step 2: Identify the initial speed (u) and final speed (v) of the train. The initial speed (u) is 20 m/s (before braking) and the final speed (v) is 0 m/s (after stopping).
Step 3: Determine the time (t) it takes for the train to stop, which is given as 5 seconds.
Step 4: Use the formula for acceleration (a): a = (v - u) / t. Substitute the values: a = (0 - 20) / 5.
Step 5: Calculate the acceleration: a = -20 / 5 = -4 m/s².

Kinematics – The study of motion, specifically how speed, time, and acceleration relate to each other.
Unit Conversion – The process of converting units from one system to another, in this case from kilometers per hour to meters per second.
Acceleration Calculation – Using the formula for acceleration, which is the change in velocity over time.