If an object is located 20 m to the right of the origin at 1:00 PM, and later the object is located 30 m to the right of the origin at 2:00 PM, then the displacement from 1:00 PM to 2:00 PM is()
A. 50 m to the right.
B. 30 m to the right.
C. 25 m to the right.
D. 20 m to the right.
E. 10 m to the right.
查看答案
A displacement vector D is given as 40.0 m long at an angle of 60.0 degrees NORTH of EAST. The Dx component and the Dy component of the vector are()
A. Dx = +34.6 m, Dy = +20.0 m.
B. Dx = +20.0 m, Dy = -34.6 m.
C. Dx = +20.0 m, Dy = +34.6 m.
Dx = -34.6 m, Dy = +20.0 m.
E. Dx = +34.6 m, Dy = -20.0 m.
The precision and number of significant figures in 1.003 km is ()
A. precision = .0001 km, significant figure = 4.
B. precision = .001 km, significant figure = 4.
C. precision = .0001 km, significant figure = 3.
D. precision = .001 km, significant figure = 3.
E. precision = .0001 km, significant figure = 2.
The precision and number of significant figures in 0.0045 mm is ()
A. precision = .0001 mm, significant figures = 4.
B. precision = .001 mm, significant figures = 4.
C. precision = .0001 mm, significant figures = 3.
D. precision = .001 mm, significant figures = 3.
E. precision = .0001 mm, significant figures = 2.
Which of the SI prefixes is used to indicate 109?()
A. kilo
B. mega
C. giga
D. tera
E. nano
微信支付 
支付宝支付