Question

A body is thrown vertically upwards from a top of tower of height 40m with speed 10ms-1. Then (
g = 10ms –2)
(A) Velocity of body is zero after 2s
(B) Time of flight of body is 4s
(C) Distance travelled by body is 50m
(D) Body strikes the ground with velocity 30ms -1​

Answer 1

Question

A body is thrown vertically upwards from a top of tower of height 40m with speed 10ms-1. Then (

g = 10ms –2)

(A) Velocity of body is zero after 2s

(B) Time of flight of body is 4s

(C) Distance travelled by body is 50m

(D) Body strikes the ground with velocity 30ms -1

Answer

• Height(h) = 40m
• initial velocity(u) = 10 ms-1

For a body thrown vertically upwards from the top of a tower,

$\sf{h = - ut + \frac{1}{2} g {t}^{2}}$

Substitute the values,

40 = -10t + 1/2(10)$\sf{t}^{2}$

Solving for t, we get t = 4s

There fore the answer is option (B)

Answer 2

Given : A body is thrown vertically upwards from a top of tower of height 40m with speed 10m/s  ( g = 10m/s ²)

To Find :  Correct option

(A) Velocity of body is zero after 2s

(B) Time of flight of body is 4s

(C) Distance travelled by body is 50m

(D) Body strikes the ground with velocity 30m/s

Solution:

A body is thrown vertically upwards from a top of tower of height 40m with speed 10m/s  ( g = 10m/s ²)

V = U + at

U = 10 m/s

a = - g = -10 m/s ²

t = 2 sec

=> V =  10   -10 * 2

=> V =  - 10  m/s

Velocity of body is zero after 2s  - INCORRECR

Time to reach peak  

0 = 10 - 10(t)

=> t = 1 sec

time to came back at same position =    1 + 1 = 2 sec

Velocity = 10 m/s down ward

S = 40 m

S = Ut + (1/2)at²

40 = 10 * t  + (1/2) * 10 (t)²

=> t²  + 2t  - 8  = 0

=> t =  -4  ,  2    -4 not possible

Hence t = 2

so 2 + 2 = 4 sec

Time of Flight = 4 sec    

Time of flight of body is 4s   - CORRECT

V² - U² = 2as

=>  - 10²  = 2 (-10)S  =>  S = 5    ( distance to reach at top )

Hence Distance travelled by body  

= 5 + 5 + 40

= 50  m

Distance travelled by body is 50m  - CORRECT

V = U + at

=> V =  10 + (-10) 4

=> V = - 30 m/s

Body strikes the ground with velocity  30 m/s  CORRECT

Learn More:

A ball thrown vertically up from the top of a tower reaches the ground ...

brainly.in/question/8127453

A body is thrown vertically upwards from the top of a tower from point ...

brainly.in/question/1661995

A ball is thrown up vertically returns to the thrower after 6 s . Find: 1 ...

brainly.in/question/9114082