A 250.0 kg rock falls off a 40.0 m cliff. What is the kinetic energy of the rock just before it hits the ground (hint: conservation of energy)?

kinetic energy body when it hits the ground is 98000 joule

1000joule = 1 kilojoule

, kinetic energy body when it hits the ground is 98  kilo-joule

Step-by-step explanation:

conservation of energy states that total energy of a system remains constant.

Potential energy of body = mgh

m = mass

g = gravitational pull = 9/8 m/s^2

h = height

kinetic energy = 1/2 mv^2

where v is the velocity of body

Total energy for this at any point is sum of potential energy and kinetic energy

total energy at height h

v= 0

PE = 250*9.8*40= 98,000

KE = 1/2 m0^2  = 0

total energy at when ball hits the ground

h=0

PE = 250*9.8*0 =

KE = 1/2 mv^2  

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Applying conservation of energy

Total energy at height h = total energy at ground

98000 = KE

Thus, kinetic energy body when it hits the ground is 98000 joule

1000joule = 1 kilojoule

, kinetic energy body when it hits the ground is 98  kilo-joule

2 & 7

step-by-step explanation:

he climbs 300 ft/hr at a constant rate. the peak is at 1,500 ft.

when going up, he reaches 600 ft in 2 hours. remember, that he is going in a constant rate. divide 600 with 300:

600/300 = 2

assuming that he takes the same route back (meaning that it's a 1500 ft route back, you can solve.

note also that you are solving when he gets back to 600 ft after he reaches the peak.

first, find the amount of hours it takes to get up the peak. divide the total amount (1500), with the ft/her (300) to get the amount of hours (x):

1500/300 = x

x = 5

it takes jamie 5 hours to get up. now, he is returning down, and reaches 600 (his current destination). remember that he climbs at a constant 300 ft/hr. divide 600 with 300:

600/300 = x

x = 2

now add the two numbers together.

x = 5 + 2 = 7

jamie takes 7 hours to go up the mountain and reach his current position when descending.

(total amount/constant rate) = (time).

remember that it is a constant rate, so in total, when he gets back down the mountain, it will take the same amount of time as when he goes up. the total amount for the round trip is: 5 + 5 = 10.

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