Physics, 02.07.2019 21:30 ayoismeisalex

If a 2 kg ball is at the edge of a 40 meter cliff and falls off, how much kinetic energy will the ball have when it hits the ground?

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Answer from: kacr7292

m = mass of the ball at the edge of the cliff = 2 kg

h = height of the cliff from where the ball falls off = 40 m

g = acceleration due to gravity = 9.8 m/s²

gravitational potential energy of the ball at the top of the cliff is given as

PE = mgh

inserting the above values in the formula

PE = (2) (9.8) (40)

PE = 784 J

KE = kinetic energy of the ball as hits the ground.

initially at the top of cliff , the ball has no kinetic energy and only potential energy. as the ball falls down the cliff , the speed of ball increase which increases the kinetic energy and potential energy decrease by same amount as the height above the ground decrease.

using conservation of energy

kinetic energy of ball as it hits the ground = Potential energy of the ball at the top of cliff

KE = PE

KE = 784 J

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 earths atmosphere is made up of nitrogen and oxygen. solids can turn into gasses through a process called sublimation. sublimation is the transition of a substance directly from the solid to the gas phase, without passing through the intermediate liquid phase.

hope this : d

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If a 2 kg ball is at the edge of a 40 meter cliff and falls off, how much kinetic energy will the ba...

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