if you make an electromagnet using a battery circuit and a steel nail, how can you increase its magnetic strength?

a.
replace the nail with a copper rod

b.
wrap more coils of wire around the nail

c.
use a longer nail

d.
remove the plastic insulation from the wire coil

Agardener uses a wheelbarrow to move soil from a truck to his garden. on the first trip from the truck to the garden, the wheelbarrow is half-full of soil and the gardener applies a certain force to cause it to accelerate. on the second trip, the wheelbarrow is full of soil. although the gardener applies the same amount of force to the wheelbarrow, he cannot move it with the same rate of acceleration. what should the gardener do to move the wheelbarrow at the same rate of acceleration for the second trip?

Molten iron fills a mould, which has a volume of 200 cm cubed. calculate the volume when the iron cools and solidifies.

Follow these directions and answer the questions. 1. set up the ripple tank as in previous investigations. 2. bend the rubber tube to form a "concave mirror" and place in the ripple tank. the water level must be below the top of the hose. 3. generate a few straight pulses with the dowel and observe the reflected waves. do the waves focus (come together) upon reflection? can you locate the place where the waves meet? 4. touch the water surface where the waves converged. what happens to the reflected wave? 5. move your finger twice that distance from the hose (2f = c of c, center of the curvature) and touch the water again. does the image (the reflected wave) appear in the same location (c of c)? you may have to experiment before you find the exact location. sometimes it is hard to visualize with the ripple tank because the waves move so quickly. likewise, it is impossible to "see" light waves because they have such small wavelengths and move at the speed of light. however, both are examples of transverse waves and behave in the same way when a parallel wave fronts hit a curved surface.