A0.60-kilogram softball initially at rest is hit with a bat. the ball is in contact with the bat for 0.20 second and leaves the bat with a speed of 25 meters per second. what is the magnitude of the average force exerted by the ball on the bat?
a. 15 n
b. 3.0 n
c. 75 n
d. 8.3 n

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.

The boy of mass 30 kg is at r1= 2 meters from the fulcrum. of the girl is 45 kg, at what r2 must she sit so that they are balanced ?

Unpolarized light of intensity so passes through two sheets of polarizing material whose transmission axes make an angle of 60∘ with each other as shown in the figure. what is the intensity of the transmitted beam, st?