Grade 11Mechanics

A stone dropped from a certain height can reach the ground in 5s. It is stopped after 3 seconds of its fall and then allowed to fall again. Find the time taken by the stone to reach the ground for the remaining distance.

Arathy.A

9 Years agoGrade 11

4 Answers

Hamza

9 Years ago

S=ut+1/2at×t1/2+a×t×t125mts so height from which object is dropped is 125mts125/5×3=45mtsDistance left to be traveled is 125-45=80mtsTherefore time taken=√(2s/a)=4seconds ansSince uis the initial velocity it is zero in all the cases

vinay sharma

9 Years ago

remaining height =1/2g5x5−1/2g3x3 = 125−45=80

time taken =80=1/2gtxt

txt=16

t=4

hence time taken for remaining journey=4 sec

Zubair

9 Years ago

First find the total height covered by the stone in 5seconds.

Which can be calculated as

h=Vit+0.5gt²

since stone is dropped its initial velocity will be 0

therefore

h=0.5gt²

since t=5

H=122.5m is the total height covered by the stone in 5sec.

Now find the distance covered in 3sec by using procedure:

h=0.5(9.8)(3)²=44.1m is the distance covered in 3sec.

now subtract Distance From Height you will get remaining distance which is to be covered

122.5-44.1=78.4m(now we want the time for this remaining distance)

Since h=0.5gt²

T=(2h/g)^1/2

T={2(78.4)/9.8}^0.5=4sec

Hope You Will Understand.

shifa

7 Years ago

Because parachute has a more surface area than the stone

this is the easy answer i guess

i hope you understood

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A stone dropped from a certain height can reach the ground in 5s. It is stopped after 3 seconds of its fall and then allowed to fall again. Find the time taken by the stone to reach the ground for the remaining distance.

Arathy.A

4 Answers

Hamza

vinay sharma

Zubair

shifa

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