Which of these questions about skateboarding can be answerd using measurements? (Apex)

A mass of 100 g stretches a spring 5 cm. If the mass is set in motion from its equilibrium position with a downward velocity of

Rudiy27

Answer:

Explanation:

Given

mass of spring $m=100\ gm$

extension in spring $x=5\ cm$

downward velocity $v=70\ cm/s$

Position in undamped free vibration is given by

$u(t)=A\cos \omega _0t+B\sin \omega _0t$

where $\omega _0^2=\frac{k}{m}$

also $\frac{k}{m}=\frac{g}{L}$

$\omega _0^2=\frac{k}{m}=\frac{9.8}{0.05}$

$\omega _0=14$

$u(t)=A\cos(14t)+B\sin(14t)$

it is given

$u(0)=0$

$u'(0)=70\ cm/s$

substituting values we get

$A=0$

$u(t)=B\sin (14t)$

$u'(t)=14B\cos (14t)$

$70=14B$

$B=\frac{10}{2}$

$B=5$

$u(t)=5\sin (14t)$

3 0

4 years ago

4 A magnet can exert a force of attraction or a force of repulsion on another magnet.

GenaCL600 [577]

Answer:

Push -repulsion

Pull - attraction

Explanation:

When two magnets are brought together, a push happens when a force of repulsion is experienced where the magnets move away from each other. This means their polarity is the same and this will cause the magnet to push away from each other.

When two magnets are brought together , a pull happens when a force of attraction is experienced where the magnets move close to each other. This means their polarity is different and thus causes the magnets to pull closer to each other.

7 0

3 years ago

All of the orbitals in a given subshell have the same value of the __________ quantum number.

Gelneren [198K]

All of the orbitals in a given subshell have the same value of the "<span>magnetic and principal" quantum number

Hope this helps!</span>

3 0

3 years ago

the length of time it takes a planet to revolve around the sun is equivalent to witch of the following?

Marina86 [1]

It really depends on how far or close the planet is from the sun

6 0

3 years ago

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6) 100 ml of water is initially at 20°C. 30,000 J of heat is added to the water. What is temperature change for the water?

vovangra [49]

The temperature change of water is equal to 71.67 °C

<h3>Explanation:</h3>

Given:

Amount of transferred energy = 30,000 K J

Mass of water = 100 ml

Initial temperature = 20°C

To find the change in temperature of water.

Formula for Heat capacity is given by

Q = m×c×Δt ........................................(1)

where:

Q = Heat capacity of the substance (in J)

m=mass of the substance being heated in grams(g)

c = the specific heat of the substance in J/(g.°C)

Δt = Change in temperature (in °C)

Δt = (Final temperature - Initial temperature) = T(f) - T(i)

Q = 30,000 J

Mass of water = m = 100 ml

1 ml = 1 g ................................................(2)

Therefore m = 100 ml = 100 g

Specific heat of water is c = 4.186 J /g.

Δt = ?

Substituting these in equation (1), we get

Q = m×c×Δt

Rearranging the terms for Δt,

Δt = $\frac{Q}{m\times c}$

Δt = $\frac{30,000}{100\times 4.186} = \frac{30,000}{418.6}= 71.67\°C$

Δt = 71.67 °C

8 0

3 years ago