Which topic is related to static mechanics? [multiple answers]

• Composite

• Building construction

• Flow speed

• Wing structure

How many significant digits are there in the number 10.001?

Which are correct answers to 1.0 + 1 with the significant figures? [multiple answers]

•  $2$  
  

•  $2\times10^0$  

• 2.0

What is the area of a circle when the radius r=1.0?

• 3

• 3.1

• 3.14

• 3.14159265359

What is the force due to gravity on earth if g=9.81m/s2 and m=10

• 98.1

• 98

• 100

• 100.0

The magnitude of a force

 $\overline{F}$  is

•  $F_x^2\cdot F_y^2$  

•  $\sqrt{F_x^2\ +\ F_y^2}$  

•  $\overline{F_x^{ }}+\overline{F_y^{ }}$  

The angle  $\theta$  of position vector  $\overline{r}\$  from the x axis is:

•  $\theta=45^o$  

•  $\theta=\tan^{-1}\left(\frac{r_x}{r_y}\right)$  

•  $\theta=\sin^{-1}\left(\frac{r_x}{r_y}\right)$  

•  $\theta=\tan^{-1}\left(\frac{r_y}{r_x}\right)$  

If F = 10 i + 10 j + 10 k and

G = 20 i + 20 j + 20 k , then F + G = ____

• 10 i + 10 j + 10 k

• 30 i + 20 j + 30 k

• – 10 i – 10 j – 10 k

• 30 i + 30 j + 30 k

What is not true about an unit vector, e.g., u?

• It is dimensionless.

• Its magnitude is one.

• It always points in the direction of positive X-axis.

• It always points in the direction of vector A.

F is 80 and is 120deg from the positive vertical y-axis. Resolve F along x and y axes and write it in vector form. F = ___________

• 80 cos (30°) i – 80 sin (30°) j

• 80 sin (30°) i + 80 cos (30°) j

• 80 sin (30°) i – 80 cos (30°) j

• 80 cos (30°) i + 80 sin (30°) j