Answer:
110 rev
Explanation:
Given:
v₀ = 32 m/s
v = 0 m/s
a = -2.25 m/s²
Find: Δx
v² = v₀² + 2aΔx
(0 m/s)² = (32 m/s)² + 2 (-2.25 m/s²) Δx
Δx = 228 m
The circumference of the tires is 2π × 0.32 m = 2.01 m. Therefore:
228 m × (1 rev / 2.01 m) = 110 rev
B. The writer didn't mention anything significant .
1) Let's call
the speed of the southbound boat, and
the speed of the eastbound boat, which is 3 mph faster than the southbound boat. We can write the law of motion for the two boats:
2) After a time
, the two boats are
apart. Using the laws of motion written at step 1, we can write the distance the two boats covered:
The two boats travelled in perpendicular directions. Therefore, we can imagine the distance between them (45 mi) being the hypotenuse of a triangle, of which
and
are the two sides. Therefore, we can use Pythagorean theorem and write:
Solving this, we find two solutions. Discarding the negative solution, we have
, which is the speed of the southbound boat.
Answer: 40.2m/sec
Work: v=p/m= 5.83kg/0.145k=40.2cm/sec