An object is 21.0 cm to the left of a lens that has a focal length of +8.50 cm. A second lens, which has a focal length of -31.0 cm, is 5.40 cm to the right of the first lens. a. Find the distance between the object and the final image formed by the second lens.
b. What is the overall magnification?
c. Is the final image real or virtual?
d. Is the final image upright or inverted?
e. Draw a figure that is compatible with the problem.

An astronaut in space cannot use a scale or balance to weigh objects because there is no gravity. but she does have devices to measure distance and time accurately. she knows her own mass is 77.4 kg , but she is unsure of the mass of a large gas canister in the airless rocket. when this canister is approaching her at 3.50 m/s , she pushes against it, which slows it down to 1.30 m/s (but does not reverse it) and gives her a speed of 2.60 m/s . what is the mass of the canister?