If a 75-kg skater starts his skate at 8.0m, at his lowest point (height = 0), what is

You need to purchase a motor to supply 400 joules [J] in 10 seconds [s]. All of the motors you can choose from are 80% efficient

kondor19780726 [428]

Answer:

32 W.

Explanation:

Power: This can be defined as the ratio of energy to time. The S.I unit of power is watt(W). The formula for power is given as,

P = W/t.................... Equation 1

Where P = power, W = work done, t = time.

Given: W = 400 J, t = 10 s.

Substitute into equation 1

P = 400/10

P = 40 W.

If the motors that is choose is 80% efficient,

P' = P(0.8)

Where P' = minimum power

P' = 40(0.8)

P' = 32 W.

5 0

3 years ago

The idea that the universe began from a single point and expanded to its current size explains a large number of observations, i

jenyasd209 [6]

The United States of green

4 0

3 years ago

Read 2 more answers

How much heat is needed to raise the temperature of 1 kg of iron from 25 degree to 30 degrees?

stiv31 [10]

Answer:300 joules

Explanation:The formula for specific heat is:

E

=

m

c

θ

, where:

E

is the energy needed in joules,

m

is the mass in kilograms,

c

is the specific heat,

θ

is the change in temperature, Celsius of Kelvin doesn't matter.

Here,

m

=

0.125

kg

c

=

480

J/kg

∘

C

θ

=

5

∘

C

, and inputting:

E

=

0.125

⋅

480

⋅

5

E

=

300

J

of energy is needed.

4 0

4 years ago

A transverse, wave travelling on a chord is represented by D=0.22sin (5.6x+34t) where D and x are inmeters and t is in seconds.

ArbitrLikvidat [17]

Answer:

a) λ = 1.12 m

b) f = 5.41 Hz

c) v = 154.54 m/s

d) A = 0.22m

e)

$v_D_{max}=7.48\frac{m}{s}\\\\v_D_{min}=-7.48\frac{m}{s}\\\\$

Explanation:

You have the following equation for a wave traveling on a cord:

$D=0.22sin(5.6x+34t)$ (1)

The general expression for a wave is given by:

$D=Asin(kx-\omega t)$ (2)

By comparing the equation (1) and (2) you have:

A: amplitude of the wave = 0.22m

k: wave number = 5.6 m^-1

w: angular velocity = 34 rad/s

a) The wavelength is given by substitution in the following expression:

$\lambda=\frac{2\pi}{k}=\frac{2\pi}{5.6m^{-1}}=1.12m$

b) The frequency is:

$f=\frac{\omega}{2\pi}=\frac{34s^{-1}}{2\pi}=5.41Hz$

c) The velocity of the wave is:

$v=\frac{\omega}{k}=\frac{34s^{-1}}{0.22m^{-1}}=154.54\frac{m}{s}$

d) The amplitude is 0.22m

e) To calculate the maximum and minimum speed of the particles you obtain the derivative of the equation of the wave, in time:

$v_D=\frac{dD}{dt}=(0.22)(34)cos(5.6x+34t)\\\\v_D=7.48cos(5.6x+34t)$

cos function has a minimum value -1 and maximum +1. Then, you obtain for maximum and minimum velocity:

$v_D_{max}=7.48\frac{m}{s}\\\\v_D_{min}=-7.48\frac{m}{s}\\\\$

6 0

3 years ago

A simple pendulum is used to determine the acceleration due to gravity at the surface of a planet. The pendulum has a length of

Dafna1 [17]

Answer:

- pendulum use to determine acceleration

Explanation:

by calculating need to understand first the problem

the length is measure to be 2s

the lenght is also 2

2 obtainer on invistigation the most nearly is 8.

5 0

3 years ago