1)The period of a wave is $2500.10^{-6} s $ ,what is the frequencey of this wave ?
A. 400 Hz
B. 600 Hz
C. 1200 Hz
D. 2500 Hz
2) A car has a speed 10 m/s ,start to slow at acceleration of $1 m/s^{2}$ ,witch distance can move before stopping?
A.10 m
B.25 m
C.50 m
D.75 m
3) a man makes a lap around 400 m track in time 50 s.what is his average speed?
A.2 m/s
B.4 m/s
C.8 m/s
D.12 m/s
4) A metal bar is 100 cm long at 20 C ,we heated this bar at 40 C ,what is the increase in length if the linear exponsion coefficient of this metal is $2.10^{-5 }C^{-1}$.
A. $10^{-5 }$
B. $2.10^{-5 }$
C. $10^{-4}$
D. $4.10^{-4 }$
5) A car starts with speed null at constant acceleration $4m/s^{2}$ ,find the speed of the car at the end of 10 s?
A. 5 m/s
B.10 m/s
C.15.25 m/s
D.40 m/s
6) the speed of light in glass is $2.10^{8} $ what is the refractive index of glass?
A.n=1.5
B.n=2
C.n=3
D.n=4
Ansewr key :
1.A
2.C
3.C
4.C
5.D
6.A
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