Physics, 04.12.2019 04:31 potatonene

Fr = 12 cm, m = 360 g, and m = 70 g (below), find the speed of the block after it has descended 50 cm starting from rest. solve the problem using energy conservation principles. (treat the pulley as a uniform disk.) solve the problem using energy conservation principles. (b) repeat (a) with r = 5.0 cm.

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Answer from: tatemcgee

The speed of the block is 1.65 m/s.

Explanation:

Given that,

Radius = 12 cm

Mass of pulley= 360 g

Mass of block = 70 g

Distance = 50 cm

(a). We need to calculate the speed

Using energy conservation

P.E=K.E

P.E=mgh

$K.E=\dfrac{1}{2}mv^2+\dfrac{1}{2}I\omega^2$

$K.E=\dfrac{1}{2}mv^2+\dfrac{1}{2}I\times(\dfrac{v}{r})^2$

$K.E=\dfrac{1}{2}mv^2+\dfrac{1}{2}\times0.5Mr^2\times(\dfrac{v}{r})^2$

$K.E=\dfrac{1}{2}mv^2+\dfrac{1}{2}\times0.5M\times v^2$

$K.E=\dfrac{1}{2}v^2(m+0.5M)$

Put the value into the formula

$mgh=\dfrac{1}{2}v^2(m+0.5M)$

$v^2=\dfrac{2mgh}{m+0.5M}$

$v=\sqrt{\dfrac{2mgh}{m+0.5M}}$

$v=\sqrt{\dfrac{2\times70\times10^{-3}\times9.8\times50\times10^{-2}}{70\times10^{-3}+0.5\times360\times10^{-3}}}$

$v=1.65\ m/s$

(b), We need to calculate the speed of the block

When r = 5.0 cm

Here, The speed of the block is independent of radius of pulley.

Hence, The speed of the block is 1.65 m/s.

Answer from: Quest

answer: the correct answer is 1.

explanation: there are various process in which a radioactive nuclei decays:

1) alpha decay: in this process, a heavier nuclei decays into lighter nuclei by releasing alpha particle. the mass number is reduced by 4 units.

$_a^z\textrm{x}\rightarrow _{a-2}^{z-4}+_2^4\alpha$

2) electron capture: in this decay process, a parent nuclei absorbs an electron and gets converted into a neutron. simply, a proton and an electron combines together to form a neutron. mass number does not change in this process.

$_a^z\textrm{x}+_{-1}^0\textrm{e}\rightarrow _{z-1}^a\textrm{y}$

3) gamma ray emission: it is a decay process in which an unstable nuclei gives excess energy by a spontaneous electromagnetic process. this decay releases $\gamma -radiations$ . this process does not change the mass number.

$_a^z\textrm{x}^*\rightarrow _a^z\textrm{x}+_0^0\gamma$

4) positron emission: it is a type of decay process, in which a proton gets converted to neutron and an electron neutrino. this is also known as $\beta ^+$ -decay. in this the mass number remains same.

$_a^z\textrm{x}\rightarrow _{z-1}^a\textrm{y}+_{+1}^0e$

from the above information, we see that only alpha-decay is producing a change in the mass number of the nucleus.

Answer from: Quest

the unit of the measure = $\frac{j}{kgk}$

explanation:

the property that is quantified by the energy needed per of material to raise the temperature by one.

si unit of energy = joule (j)

si unit of temperature = kelvin (k)

si unit of mass of material = kilogram (kg)

the property that is quantified by the energy needed per of material to raise the temperature by one is called specific heat.

the unit of specific heat is $\frac{j}{kgk}$

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Fr = 12 cm, m = 360 g, and m = 70 g (below), find the speed of the block after it has descended 50 c...

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