Acceleration usually has the symbol a. It is a vector. What is the correct way

A biker pedals hard to ride his bike to the top of a 44 m hill. He decides to let his bike coast down the hill, and is having so

Vanyuwa [196]

The biker's speed at the top of the second hill is 25.8 m/s

Explanation:

The problem can be solve by applying the law of conservation of energy. In absence of frictional forces, the total mechanical energy of the bike (the sum of potential energy + kinetic energy) must be conserved. So we can write:

$U_i +K_i = U_f + K_f$

where

$U_i$ is the initial potential energy at the top of the first hill

$K_i$ is the initial kinetic energy at the top of the first hill

$U_f$ is the final potential energy at the top of the second hill

$K_f$ is the final kinetic energy at the top of the second hill

We can rewrite the equation as:

$mgh_i + \frac{1}{2}mu^2 = mgh_f + \frac{1}{2}mv^2$

where:

m is the mass of the bike

$g=9.8 m/s^2$ is the acceleration of gravity

$h_i = 44 m$ is the height of the first hill

u = 0 m/s is the speed at the top of the first hill

$h_f = 10 m$ is the height of the second hill

v is the speed at the top of the second hill

And solving for v, we find:

$mgh_i = mgh_f + \frac{1}{2}mv^2\\v^2=\sqrt{2g(h_i-h_f)}=\sqrt{2(9.8)(44-10)}=25.8 m/s$

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3 years ago

You stand on a frictional platform that is rotating at 1.1 rev/s. Your arms are outstretched, and you hold a heavy weight in eac

bezimeni [28]

Answer:

a) The resulting angular speed of platform is 1.38 rev/sec

b) The change in kinetic energy of the system is 53 J.

Explanation:

This question is incomplete. The complete question will be:

You stand on a frictional platform that is rotating at 1.1 rev/s. Your arms are outstretched, and you hold a heavy weight in each hand. The moment of inertia of you, the extended weights, and the platform is 8.8 kg · m2. When you pull the weights in toward your body, the moment of inertia decreases to 7.0 k g .m 2

a) What is the resulting angular speed of the platform? Answer in units of r e v / s .

b)What is the change in kinetic energy of the system? Answer in units of J.

<h3>ANSWER:</h3>

a)

we know that:

Angular Momentum = L = Iω

From conservation of momentum:

Lo = Lf

(Io) (ωo) = (If) (ωf)

ωf = (Io) (ωo)/(If)

ωf = (8.8 kg.m²)(1.1 rev/s)/(7.0 kg.m²)

b)