Question

1. The speed of a particle when it is at its greatest height is 1/2

times its speed at

half the max height. Its angle of projection is ________________ from

horizontal plane.
2. The length, breath and thickness of a rectangular sheet of metal are 4.2341 m,

1.0005 mm and 2.01 cm respectively. It have ______________ significant

digit in its volume of sheet.

​

Answer 1

Answer:

1. The velocity of a particle when it is at its greatest height

The speed of a projectile when it is at its greatest height is 2/5 times its speed at half the maximum height.

Let v be velocity of a projectile at maximum height H

v = ucosθ

According to given problem, v =  

2

u

​

 

∴  

2

u

​

=ucosθ⇒cosθ=  

2

1

​

 

θ=60  

o

 

2. =2×(L×B+B×T+T×L)

∴A=2×(4.234×1.005+1.005×0.0201+0.0201×4.234)

∴A=2×(4.2552+0.0202+0.0851)

∴A=8.721m  

2

 

∴A=8.721m  

2

  to correct significant digits

V=L×B×T

∴V=4.234×1.005×0.0201

∴V=0.0855m  

3

 to correct significant digits

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