The answer is 41.25 mph.

The average speed (v) can be expressed as:
v = D/T
where
D is total distance: D = d1 + d2 + d3 + d4
T is total time: T = t1 + t2 + t3 + t4

Now let's calculate distances using the formula: d = v * t:
d1 = v1 * t1 = 20.0 * 0.500 = 10 mi
d2 = v2 * t2 = 40.0 * 1.00 = 40 mi
d3 = v3 * t3 = 30.0 * 0.500 = 15 mi
d4 = v4 * t4 = 50.0 * 2.00 = 100 mi

Thus, the average speed is:
$v= \frac{D}{T}= \frac{d1 + d2 + d3 +d4}{t1+t2+t3+t4} = \frac{10+40+15+100}{0.500+1.00+0.500+2.00}= \frac{165}{4} = 41.25 mph$

4 0

2 years ago

A ball thrown horizontally from a point 30.0 m above the ground strikes the ground after travelling a horizontal distance of 18.

AURORKA [14]

The components of the ball's position $r$ at time $t$ are

$\begin{cases}r_x(t)=v_{0x}t\\v_y(t)=30.0-4.9t^2\end{cases}$

The ball stops 18.0 m from where it began, so that

$\begin{cases}18.0=v_{0x}t\\0=30.0-4.9t^2\end{cases}$

From the second equation, we can show that the ball travels for about $t=2.47$ seconds, which means it was initially thrown with a horizontal velocity of

$18.0\,\mathrm m=v_{0x}(2.47\,\mathrm s)\implies v_{0x}=7.29\,\dfrac{\mathrm m}{\mathrm s}$

7 0

3 years ago

When working with a razor blade or exacto knife --

stich3 [128]

Answer:

last answer

Explanation:

gripping it with the blade facing downward is the most efficient and safe way to use an exacto knife

6 0

2 years ago