Answer:
Explanation:
Given
Cross-sectional area of wire
Extension of wire
Extension in a wire is given by
where,
for same force, length and material
Divide (i) and (ii)
A ball of mass of 0.5kg is dropped from a height of 2m.
1 answer:
Answer:
6.3m/s
Explanation:
Given parameters:
Mass of the ball = 0.5kg
Height = 2m
Unknown:
Velocity when the ball hits the ground = ?
Solution:
Since the potential energy is transformed into kinetic energy;
P.E = K.E
mgh = m v²
cancelling m;
gh = v²
v² = 2gh
v = √2gh
Insert the parameters and solve;
v = √2gh = √ 2 x 9.8 x 2 = 6.3m/s
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Answer:
The near point of an eye with power of +2 dopters, u' = - 50 cm
Given:
Power of a contact lens, P = +2.0 diopters
Solution:
To calculate the near point, we need to find the focal length of the lens which is given by:
Power, P =
where
f = focal length
Thus
f =
f = = + 0.5 m
The near point of the eye is the point distant such that the image formed at this point can be seen clearly by the eye.
Now, by using lens maker formula:
where
u = object distance = 25 cm = 0.25 m = near point of a normal eye
u' = image distance
Now,
Solving the above eqn, we get:
u' = - 0.5 m = - 50 cm