5. If you walk 70 meters north in 5 minutes and 20 meters south in 15 seconds. What was the average

Describe how work is done by a skater pulling in her arms during a spin. In particular, identify the force she exerts on each ar

liberstina [14]

Answer:

∑ τ =0, L₀ = $L_{f}$

Explanation:

In a circular turning movement, when the arms are extended and then contracted in two possibilities:

- They are lowered the force of gravity is what pulls them, the tension of the muscle becomes zero to allow this movement.

In this movement the force is vertical(gravity) and the movement of the center of mass of each arm is vertical, so that the work is the weight value of the arm by the distance traveled by the center of mass.

- Another possibility is that the arms have stuck to the body, in this case the person's muscles perform the force, this force is horizontal and the displacement is the horizontal of the center of mass of the arms from the extended position to the contracted

In these movements the torque of the external force is equal for each arm, but in the opposite direction, so they are canceled where a net torque of zero, this causes the angular momentum to be preserved, which changes is the moment of inertia of the system and therefore you must also change the angular velocity to keep your product constant

∑ τ =0

L₀ = $L_{f}$

I₀ w₀ = I w

4 0

3 years ago

Oxygen and nutrients are moved through the body by the: a. circulatory system c. lymphatic system b. digestive system d. reprodu

vagabundo [1.1K]

A. The Circulatory System.

3 0

3 years ago

Where is the resistor located on the diagram?

Andrej [43]

The answer is B hope this helps

5 0

4 years ago

Read 2 more answers

Design a solution that can monitor and minimize the melting of sea ice caused by human activity

dedylja [7]

Answer:

CO2 emissions from fossil fuel burning should be minimized at all cost. The CO2 are gotten when the carbons from hydrocarbons react with air(oxygen). This gas erodes the ozone layer which makes the melting of ice caps faster due to increased amount of heat radiations on the earth. This is the only best and permanent solution to the reduction of the amount of heat rays on the earth which is a global problem.

Objects which reflects back the sunrays could also be inserted into the sea to prevent the melting of the ice caps.

7 0

3 years ago

A bicycle rider has a speed of 19.0 m/s at a height of 55.0 m above sea level when he begins coasting down hill. The mass of the

lukranit [14]

Answer:

The mechanical energy of the rider at any height will be 6.34 × 10⁴ J.

Explanation:

Hi there!

The mechanical energy of the rider is calculated as the sum of the gravitational potential energy plus the kinetic energy. Since there are no dissipative forces (like friction), the mechanical energy of the rider at a height of 55.0 m above the sea level will be the same at a height of 25.0 m (or at any height), because the loss in potential energy will be compensated by a gain in kinetic energy, according to the law of conservation of energy.

Then, calculating the potential and kinetic energy at 55.0 m and 19 m/s, we can obtain the mechanical energy that will be constant:

Mechanical energy = PE + KE

Where:

PE = potential energy.

KE = kinetic energy.

The potential energy is calculated as follows:

PE = m · g · h

Where:

m = mass of the object.

g = acceleration due to gravity.

h = height.

Then, the potential energy of the rider will be:

PE = 88.0 kg · 9.81 m/s² · 55.0 m = 4.75 × 10⁴ J

The kinetic energy is calculated as follows:

KE = 1/2 · m · v²

Where "m" is the mass of the object and "v" its velocity. Then:

KE = 1/2 · 88.0 kg · (19.0 m/s)²

KE = 1.59 × 10⁴ J

The mechanical energy of the rider will be:

Mechanical energy = PE + KE = 4.75 × 10⁴ J + 1.59 × 10⁴ J = 6.34 × 10⁴ J

This mechanical energy is constant because when the rider coast down the hill, its potential energy is being converted into kinetic energy, so that the sum of potential energy plus kinetic energy remains constant.

5 0

3 years ago