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3 years ago

Why does the skier's velocity increase as he races downhill?

1 answer:

3 0

Downhill skiing is also called alpine skiing. It involves high speed and quick turns down a sloped terrain. The skier gains speed by converting gravitational potential energy into kinetic energy of motion. So the more a skier descends down a hill, the faster he goes.

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If a force does a positive amount of work on an object, does the object’s speed increase, decrease, or remain the same? Justify

iris [78.8K]

Answer:

see that there is no dependence on speed, so the work remains constant

Explanation:

Work is defined by the expression

W = F. d

where the boldface indicates vectors, this equation can be written in scalar form

W = f d cos θ

where θ is the angle between force and displacement.

We see that there is no dependence on speed, so the work remains constant

The power is

P = W / t

P = f d / t

p = F v

we see that the power is the one that depends on the speed of the body

6 0

3 years ago

Which of newtons laws accounts for the following statement " Negative acceleration is proportional to applied braking force "

fenix001 [56]

I believe that would be his second law!

4 0

4 years ago

A block of mass m slides down a frictionless track, then around the inside of a circular loop-the-loop of radius R. From what mi

Oliga [24]

Answer:

$H = \frac{5}{2}R$

Explanation:

As we know that if the block will complete the circular motion of the path then the speed at the bottom most part of the path must be equal to

$v = \sqrt{5Rg}$

now we know that

velocity at the bottom of the path is due to conversion of potential energy to kinetic energy

so we can say it is given as

$U = KE$

$mgH = \frac{1}{2}mv^2$

now we have

$mgH = \frac{1}{2}m(5Rg)$

$H = \frac{5}{2}R$

3 0

3 years ago

A box is given a push so that it slides across the floor. How far will it go, given that the coefficient of kinetic friction is

maksim [4K]

D = v^2 / 2ug

d= 3.5^2 / 0,15 x 9.8 m/s^2

the answer should be around 4.2m

hope this helps

8 0

3 years ago

A river flows due east at 1.60 m/s. A boat crosses the river from the south shore to the north shore by maintaining a constant v

Citrus2011 [14]

Answer:

part (a) $v\ =\ 10.42\ at\ 81.17^o$ towards north east direction.

part (b) s = 46.60 m

Explanation:

Given,

velocity of the river due to east = $v_r\ =\ 1.60\ m/s.$
velocity of the boat due to the north = $v_b\ =\ 10.3\ m/s.$

part (a)

River is flowing due to east and the boat is moving in the north, therefore both the velocities are perpendicular to each other and,

Hence the resultant velocity i,e, the velocity of the boat relative to the shore is in the North east direction. velocities are the vector quantities, Hence the resultant velocity is the vector addition of these two velocities and the angle between both the velocities are $90^o$

Let 'v' be the velocity of the boat relative to the shore.

$\therefore v\ =\ \sqrt{v_r^2\ +\ v_b^2}\\\Rightarrow v\ =\ \sqrt{1.60^2\ +\ 10.3^2}\\\Rightarrow v\ =\ 10.42\ m/s.$

Let $\theta$ be the angle of the velocity of the boat relative to the shore with the horizontal axis.

Direction of the velocity of the boat relative to the shore. $\therefore Tan\theta\ =\ \dfrac{v_b}{v_r}\\\Rightarrow Tan\theta\ =\ \dfrac{10.3}{1.60}\\\Rightarrow \theta\ =\ Tan^{-1}\left (\dfrac{10.3}{1.60}\ \right )\\\Rightarrow \theta\ =\ 81.17^o$

part (b)

Width of the shore = w = 300m

total distance traveled in the north direction by the boat is equal to the product of the velocity of the boat in north direction and total time taken

Let 't' be the total time taken by the boat to cross the width of the river. $\therefore w\ =\ v_bt\\\Rightarrow t\ =\ \dfrac{w}{v_b}\\\Rightarrow t\ =\ \dfrac{300}{10.3}\\\Rightarrow t\ =\ 29.12 s$

Therefore the total distance traveled in the direction of downstream by the boat is equal to the product of the total time taken and the velocity of the river $\therefore s\ =\ u_rt\\\Rightarrow s\ =\ 1.60\times 29.12\\\Rightarrow s\ =\ 46.60\ m$

7 0

4 years ago

Why does the skier's velocity increase as he races downhill?​

Why does the skier's velocity increase as he races downhill?