A missile travels at a speed of 1260 km/h. How many metres does it travel in one second?

Introduction / Context:
Once again we work with speed in km/h and convert it to metres per second to find how far an object moves in one second. Missile speed problems mirror real world high speed travel and are useful to test if a candidate can comfortably move between units and interpret the magnitude of a speed correctly. The central idea is to apply the unit conversion formula carefully and then apply distance = speed * time for one second.

Given Data / Assumptions:

Missile speed = 1260 km/h.
We need the distance covered in one second, in metres.
The missile is assumed to move at uniform speed over this short interval.
Use 1 kilometre = 1000 metres and 1 hour = 3600 seconds.

Concept / Approach:
The conversion from km/h to m/s uses the same principle: multiply by 1000 to change kilometres to metres and divide by 3600 to convert hours to seconds. Once we convert 1260 km/h to m/s, the distance travelled in one second is numerically equal to that speed in m/s, because distance in one second equals speed times 1 second. We should also sanity check the value against a known reference, such as 360 km/h being 100 m/s, to see whether the final number is realistic.

Step-by-Step Solution:
Step 1: Convert speed from km/h to m/s. speed_mps = 1260 * 1000 / 3600. This gives speed_mps = 1260000 / 3600. Step 2: Simplify the fraction. 1260000 / 3600 = 350. So the missile moves at 350 m/s. Step 3: Distance in one second. distance = speed * time = 350 * 1 = 350 metres.

Verification / Alternative check:
We know 360 km/h corresponds to 100 m/s. The speed 1260 km/h is 3.5 times 360 km/h. Therefore, the speed in m/s should be 3.5 * 100 = 350 m/s. This quick proportional reasoning confirms the detailed numerical conversion. The value also looks reasonable for a fast projectile through air and matches the chosen option exactly.

Why Other Options Are Wrong:
Options a (322 metres), b (369 metres), and c (384 metres) are not equal to 1260000 / 3600 and likely arise from approximate or incorrect mental arithmetic. They may appear close to 350 but they do not respect the clear ratio between 1260 km/h and 360 km/h. Only 350 metres correctly matches the exact conversion and the proportional argument.

Common Pitfalls:
Typical mistakes include miscalculating 1260000 / 3600, forgetting to cancel common factors, or doing the conversion with rounded intermediate values that accumulate error. Another error is to divide by 60 instead of 3600, which would give a speed ten times too large. Writing the conversion as two distinct steps and simplifying fractions carefully helps avoid these issues.

Final Answer:
Therefore, the missile travels 350 metres in one second.