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A small spherical ball of radius 0.1 mm and density 10⁴ kg m⁻³ falls freely under gravity through a distance h before entering a tank of water. If, after entering the water the velocity of ball does not change and it continue to fall with same constant velocity inside water, then the value of h will be _____ m. (Given g = 10 m s⁻², viscosity of water = 1.0 × 10⁻⁵ N-s m⁻²).
- 20.00
- 20.0
- 2.00
- 2.0
Correct answer: 20.00
Solution
The ball reaches a terminal velocity when the gravitational force is balanced by the drag force due to viscosity, which occurs after falling a certain distance h. Given the parameters, the calculations show that this distance h is 20.00 m, where the ball maintains a constant velocity in water.
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