University physics答案2023秋

第二章测试

1.A particle is moving straight along the x direction, and its position is determined by the equation , where the unit of x is meter, and the unit of t is second. Then its velocity is expressed as （ ）
A:v=20t+8 B:v=20t C:v=10t+8 D:v=10t
答案:B
2.Velocity is a vector, and speed is also a vector. （ ）
A:对 B:错 3.The magnitude of the acceleration of the object may be very large, while the magnitude of the velocity of an object can remain unchanged. （ ）
A:错 B:对 4.A warship fires the shells at tow enemy ships at the same time. It is known that the shells will fly along the parabolic orbits as shown in the figure and hit the enemy ships, assume the shells has the same initial speed, which ship will be hit first? （ ）
A:Ship A B:Ship B C:More information is needed D:Both ships will be hit at the same time 5.A car moves at constant speed in a horizontal of radius 20.0 m, making a complete circle in 7.0 s. What is the acceleration of the car? （ ）
A: B: C: D: