Q1. A 60 m ladder leans against a wall. What is the minimum force of friction essential to prevent the ladder from sliding? Presume that the force in the wall is negligible.
Q2. Two identical diverging lenses are separated by 12 cm. The focal length of each lens is -7.0 cm. An object is located 5.0 cm to the left of the lens that is on the left. Find out the final image distance relative to the lens on the right.
Q3. Radioactive isotopes frequently occur together in mixtures. Assume a 400g sample contains, with a half-life of 12 days, and, with a half-life of 4.5 days. If there are firstly twice as many calcium atoms as there are barium atoms, what will be the ratio of calcium atoms to barium atoms 3.50 weeks later?