A train moving with a speed of 72 km/h applies brakes and comes to a stop in 10 seconds. What is the magnitude of its acceleration?
Practice Questions
1 question
Q1
A train moving with a speed of 72 km/h applies brakes and comes to a stop in 10 seconds. What is the magnitude of its acceleration?
-2 m/s²
-3 m/s²
-4 m/s²
-5 m/s²
First convert speed to m/s: 72 km/h = 20 m/s. Using the formula: acceleration = (final velocity - initial velocity) / time = (0 - 20) / 10 = -2 m/s².
Questions & Step-by-step Solutions
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Q
Q: A train moving with a speed of 72 km/h applies brakes and comes to a stop in 10 seconds. What is the magnitude of its acceleration?
Solution: First convert speed to m/s: 72 km/h = 20 m/s. Using the formula: acceleration = (final velocity - initial velocity) / time = (0 - 20) / 10 = -2 m/s².
Steps: 5
Step 1: Convert the speed 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 velocity (u) and final velocity (v). The initial velocity is 20 m/s (the speed of the train before braking) and the final velocity is 0 m/s (the train stops).
Step 3: Determine the time taken to stop. The time given is 10 seconds.
Step 4: Use the formula for acceleration: acceleration = (final velocity - initial velocity) / time. Plug in the values: acceleration = (0 m/s - 20 m/s) / 10 s.
Step 5: Calculate the acceleration: acceleration = -20 m/s / 10 s = -2 m/s².
