Phyics试卷(a).docVIP

Physcis（A） Department Grade Specialty Number　　　　　　　 Name　　　　　Score 一．Fill in the blanks (40) 1. For the situation of figure, Barbara’s velocity relative to Alex is a constant vBA=52km/h and car P is moving in the negative direction of the x axis. If Alex measures a constant velocity vPA=-78km/h for car P, the velocity vPB measured by Barbara is ; If car P brakes to a stop relative to Alex (and thus the ground) in time t=10s at constant acceleration, the acceleration aPA relative to Alex is ; the acceleration aPB of car P relative to Barbara during the braking is . 2. In figure, three blocks are connected and pulled to the right on a horizontal frictionless table by a force with a magnitude of T3=65.0N. If m1=12.0kg, m2=24.0kg, and m3=31.0kg, calculate (a) the acceleration of the system is ;(b) the tensions in the interconnecting cords T1= ,T2= . 3．As shown in figure, a 1.34kg ball is connected by means of two massless strings to a vertical, rotating rod. The strings are tied to the rod and are taut. The tension in the upper string is 35N. (a) The tension in the lower string is ;(b) the net force on the ball is ;(c) the speed of the ball is . 4. A 1.50kg snowball is fired from a cliff 12.5m high with an initial velocity of 14.0m/s, directed 41.0° above the horizontal. (a)Work done on the snowball by the gravitational force during its flight to the flat ground below the cliff is ;(b) The change in the gravitational potential energy of the snowball-Earth system during the flight is ;(c) If the gravitational potential energy is taken to be zero at the height of the cliff, what is its value when the snowball reaches the ground . 5. In figure, two particles, each with mass m, are fastened to each other, and to a rotation axis at o, by two thin rods, each with length d and mass M. T