University physics答案2023秋

第一章测试

1.How many years older will you be 1.00 gigaseeond from now? (Assume a 365-day year.) （ ）
A:21.7 y B:51.7 y C:31.7y D:41.7 y
答案:C
2.Scientific notation: （ ）
A: B: C: D:
答案:B
3.

In Δ ABC, we know that D is a point on the extension line of BC, and E is the midpoint of line segment AD. If , and , then x = （ ）.

A:−1/4 B:1/4 C:−1/3 D:1/3
答案:A
4.

Vector operation. If , and , find the value of , such that the vectors and will be perpendicular to each other （ ）.

A:-2/3 B:-5/3 C:-4/3 D:-8/3
答案:C
5.

Two displacement vectors,  and , have magnitudes S=3 m and T=4 m, which of the following could not be the magnitude of the difference vector? (There may be more than one correct answer.) （　   　）.

A:9 m B:1 m C:7 m D:5 m
答案:A