# If the mass is 4.3 kg, the initial speed is 4.0 m/s, and the initial height is 8.0 m, find speed of the ball when it is at height of 7.6 m.?

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- MyRankLv 62 weeks ago
Given,

Mass (m) = 4.3kg

Initial speed (u) = 4m/sec

Initial height (hi) = 8m

Final speed (v) = ?

Final height (hf) = 7.6m

Using kinematic relation:-

v² = u² + 2gh (hi – hf)

= final speed (v) = √u² + 2g(hi – hf)

= √(4m/sec)² + 2 x 9.81m/sec² (8m-7.6m)

= √16m²/sec² + 7.848 m²/sec²

= 4.88m/sec ≈ 4.9m/sec

∴ final speed (v) = 4.9m/sec

Source(s): http://myrank.co.in/ - PinkgreenLv 73 weeks ago
Let the new speed of the ball be v m/s, then

(4.3/2)v^2+7.6(4.3)(9.81)=(4.3/2)(4^2)+8(4.3)(9.81)=>

v^2=23.848=>

v=sqr(23.848)=4.9 m/s approximately.

- oubaasLv 73 weeks ago
Conservation of energy shall apply :

V = √Vo^2+2*g*(ho-h) = √4^2+19.612*(8-7.6) = 4.88 m/sec

- billrussell42Lv 73 weeks ago
depends on the angle. Is the ball thrown upwards, downwards, or at an angle?

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