The second hand of a clock has a length of 0.30 m. What distance does the tip of the second hand sweep through in 3 minutes and 45 seconds?

A. 1.1 m
B. 1.8 m
C. 7.1 m
D. 13 m



Answer :

Let's solve the problem step-by-step.

1. Determine the total time: We need to convert the given time into seconds. The given time is 3 minutes and 45 seconds.
[tex]\[ \text{Total time in seconds} = 3 \times 60 + 45 = 180 + 45 = 225 \text{ seconds} \][/tex]

2. Calculate the number of full circles: The second hand of the clock makes a full circle (360 degrees or [tex]\( 2\pi \)[/tex] radians) every 60 seconds. To find out how many full circles the second hand completes in the given time:
[tex]\[ \text{Number of full circles} = \frac{225 \text{ seconds}}{60 \text{ seconds/circle}} = 3.75 \text{ circles} \][/tex]

3. Calculate the distance swept by the tip of the second hand: Each full circle corresponds to the circumference of the circle traced by the second hand. The circumference [tex]\( C \)[/tex] of a circle is given by:
[tex]\[ C = 2 \pi r \][/tex]
where [tex]\( r \)[/tex] is the radius of the circle. In this case, the length of the second hand is the radius:
[tex]\[ r = 0.30 \text{ meters} \][/tex]

4. Calculate the circumference:
[tex]\[ \text{Circumference} = 2 \times \pi \times 0.30 \text{ meters} \][/tex]

5. Find the total distance swept: To find the total distance the tip of the second hand sweeps, we multiply the circumference by the number of full circles:
[tex]\[ \text{Distance swept} = 3.75 \times 2 \pi \times 0.30 \text{ meters} \][/tex]

6. Evaluating the distance: Rounding to two decimal places, the distance swept by the tip of the second hand can be found as:
[tex]\[ \text{Distance swept} \approx 7.07 \text{ meters} \][/tex]

Thus, the second hand of a clock with a length of 0.30 meters sweeps through a distance of approximately 7.1 meters in 3 minutes and 45 seconds.

Therefore, the correct answer is:
[tex]\[ \boxed{7.1 \text{ meters}} \][/tex]