Figure 6 . An automobile having a mass of 1000 kg is driven into a brick wall in a safety test.
The bumper behaves like a spring of force constant 5.00 , 106 N/m and compresses
3.16 cm as the car is brought to rest. What was the speed of the car before impact,
assuming that no mechanical energy is lost during impact with the wall?
(10marks)
(a) Two waves traveling in opposite directions produce a standing wave. The indi-
vidual wave functions are
yı = 4,0 sin(3.0x – 2.0t)
Y2 = 4.0 sin(3.0.0 + 2.0t),
4​

A248-g piece of copper is dropped into 390 ml of water at 22.6 °c. the final temperature of the water was measured as 39.9 °c. calculate the initial temperature of the piece of copper. assume that all heat transfer occurs between the copper and the water. remember, the density of water is 1.0 g/m

Astone weighing 1.5 kilograms is resting on a rock at a height of 20 meters above the ground. the stone rolls down 10 meters and comes to rest on a patch of moss. the gravitational potential energy of the stone on the moss is joules.

Electric field of the earth. the earth has a net electric charge that causes a field at points near its surface equal to 150 n> c and directed in toward the center of the earth. (a) what magnitude and sign of charge would a 60-kg human have to acquire to overcome his or her weight by the force exerted by the earth’s electric field? (b) what would be the force of repulsion between two people each with the charge calculated in part (a) and separated by a distance of 100 m? is use of the earth’s electric field a feasible means of flight? why or why not?