A cross-country skier can complete a 7. 5 km race in 45 min. What is the skier’s average speed? km/h.

Physics

1 answer:

never [62]2 years ago

8 0

The average speed is a scalar quantity. The average speed of the skier is 10 km/hrs.

<h3>What is the average speed?</h3>

It is calculated by dividing the total distance by the total time elapsed.

The

$\overline{v}={\frac{\Delta x}{\Delta t}}$

Where,

$\overline{v}$ = average velocity

${\Delta x}$ = displacement = 7.5 km

${\Delta t}$ = change in time = 45 min = 0.75 hours

Put the values in the formula,

$\overline{v}={\frac{7.5 }{0.75 }}\\\\\overline{v}= 10 \rm \ km/hrs$

Therefore, the average speed of the skier is 10 km/hrs.

Learn more about average speed:

https://brainly.in/question/32459982

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Sally and Sam are in a spaceship that comes to within 17,000 km of the asteroid Ceres. Determine the force Sally experiences, in

MAXImum [283]

Answer:

0.01606 Newtons

Explanation:

r = Distance between the asteroid and Sally = 17000000 m

m₁ = Mass of the asteroid = 8.7× 10²⁰ kg

m₂ = Mass of Sally = 80 kg

G = Gravitational constant = 6.67 × 10⁻¹¹ m³/kgs²

From Newton's Universal law of gravity

$F=G\frac{m_1m_2}{r^2}\\\Rightarrow F=6.67\times 10^{-11}\times \frac{8.7\times 10^{20}\times 80}{17000000^2}\\\Rightarrow F=0.01606\ N$

The force Sally experiences is 0.01606 Newtons

8 0

2 years ago

A thin uniform rod of mass M and length L is bent at its center so that the two segments are now perpendicular to each other. Fi

Tatiana [17]

Answer:

(a) I_A=1/12ML²

(b) I_B=1/3ML²

Explanation:

We know that the moment of inertia of a rod of mass M and lenght L about its center is 1/12ML².

(a) If the rod is bent exactly at its center, the distance from every point of the rod to the axis doesn't change. Since the moment of inertia depends on the distance of every mass to this axis, the moment of inertia remains the same. In other words, I_A=1/12ML².

(b) The two ends and the point where the two segments meet form an isorrectangle triangle. So the distance between the ends d can be calculated using the Pythagorean Theorem:

$d=\sqrt{(\frac{1}{2}L) ^{2}+(\frac{1}{2}L) ^{2} } =\sqrt{\frac{1}{2}L^{2} } =\frac{1}{\sqrt{2} } L=\frac{\sqrt{2} }{2} L$

Next, the point where the two segments meet, the midpoint of the line connecting the two ends of the rod, and an end of the rod form another rectangle triangle, so we can calculate the distance between the two axis x using Pythagorean Theorem again:

$x=\sqrt{(\frac{1}{2}L)^{2}-(\frac{\sqrt{2}}{4}L) ^{2} } =\sqrt{\frac{1}{8} L^{2} } =\frac{1}{2\sqrt{2}} L=\frac{\sqrt{2}}{4} L$