Answer: f = -12 cm
Explanation: <u>Combined</u> <u>lenses</u> is an array of simple lenses with a common axis. The combination is useful for correction of optical aberrations which cannot be corrected by simple lenses.
When two lenses are in contact and are thin, focal lengths are related as:

If there is a distance between the lenses, the focal length will be:

Since the lenses in the question above are thin and in contact, the focal length of one of them will be:




-12
The focal length of the other lens is -12 cm, with the negative sign meaning it's a converging lens.
Answer: c) 0
Explanation:
Work tension is zero because in any infinitesimal time interval, the tension force is directly perpendicular to the displacement.
Answer: k = 2.07692
Explanation: Please find the attached files for the solution
Answer:
the answer is C
Explanation:
So, the formed image will be real and inverted.
Answer:
The velocity of the ball before it hits the ground is 381.2 m/s
Explanation:
Given;
time taken to reach the ground, t = 38.9 s
The height of fall is given by;
h = ¹/₂gt²
h = ¹/₂(9.8)(38.9)²
h = 7414.73 m
The velocity of the ball before it hits the ground is given as;
v² = u² + 2gh
where;
u is the initial velocity of the on the root = 0
v is the final velocity of the ball before it hits the ground
v² = 2gh
v = √2gh
v = √(2 x 9.8 x 7414.73 )
v = 381.2 m/s
Therefore, the velocity of the ball before it hits the ground is 381.2 m/s