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1. A MAN THROWS THE BRICKS TO A HEIGHT OF 12 METER WHERE THEY REACH WITH A SPEED OF 12 M/S. IF HE THROWS THE BRICKS SUCH THAT THEY JUST REACH THAT HEIGHT, WHAT PERCENTAGE OF ENERGY WILL BE SAVED?

a)29%

b)46%

c)38%

d)50%

2. A FORCE F=(2i + j + 3k)N ACTS ON A PARTICLE OF MASS 1 Kg FOR 2 seconds. IF INITIAL VELOCITY OF PARTICLE IS

u= (2i +j) m/s, speed of particle at the end of 2s will be

a)12m/s

b)6m/s

c)9m/s

d)4m/s

saumya shivhare

saumya shivhare , 15 Years ago

Grade 11

1 Answers

Chetan Mandayam Nayakar

if speesd at 12m is 12m/s and bricks travel a further distance before coming to rest 12²=2gh,h=7.2, therefore,energy saved =7.2/19.2= 38%

v=u+at

v= (2+(2*2))i +(1+(2*1))j +(3*2)k, therefore speed²=36+9+36=81,speed=9m/s

Last Activity: 15 Years ago

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Mechanics> WPE...

saumya shivhare , 15 Years ago

Chetan Mandayam Nayakar

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