Answer:
<h2>45cm</h2>Explanation:
A converging mirror is also known as a concave mirror. For a concave mirror, its focal length and the image distance are both positive.
Using the mirror formula as shown to get the object distance;
f is the focal length of the mirror
u is the object distance
v is the image distance
Given f = 30cm and v = 2u (The image formed is twice the size of the pencil)
Substituting this values in the formula to get u we have;
Cross multiplying we have;
2u = 90
Dividing both sides by 2;
2u/2 = 90/2
u = 45cm
The distance of the object from the mirror is 45cm
Answer:
51.2 mi/h
Explanation:
Total distance, d = 100 miles
First 60 miles with speed 55 mi/h
Next 40 miles with speed 75 mi/h
Time taken for first 60 miles, t1 = 60 / 55 = 1.09 h
Time taken for 40 miles, t2 = 40 / 75 = 0.533 h
Time spent to get stuck, t3 = 20 min = 0.33 h
Total time, t = t1 + t2 + t3 = 1.09 + 0.533 + 0.33 = 1.953 h
The average speed is defined as the ratio of total distance traveled to the total time taken.
Average speed =
Thus, the average speed of the journey is 51.2 mi/h.
Explanation:
(a) Displacement of an object is the shortest path covered by it.
In this problem, a student is biking to school. She travels 0.7 km north, then realizes something has fallen out of her bag. She travels 0.3 km south to retrieve her item. She then travels 0.4 mi north to arrive at school.
0.4 miles = 0.64 km
displacement = 0.7-0.3+0.64 = 1.04 km
(b) Average velocity = total displacement/total time
t = 15 min = 0.25 hour
Hence, this is the required solution.