The Young modulus of the metal in a wire is $1.8 \times 10^{11}\ \text{Pa}$. The wire is stretched and the strain produced is $8.2 \times 10^{-4}$. Calculate the stress, in $\text{GPa}$.
An electromagnetic wave has a frequency of $12\ \text{THz}$. Calculate the wavelength, in $\mu\text{m}$.
State which region of the electromagnetic spectrum corresponds to this frequency.
Object B lies on a horizontal surface. Two forces act on B in this horizontal plane. The forces are drawn to scale in Fig. $1.1$.
Object B lies on a horizontal surface. Two forces act on B in this horizontal plane. The force diagram in Fig. 1.1 is drawn to scale. A $7.5\,\text{N}$ force acts towards north and a $2.5\,\text{N}$ force acts at $30^\circ$ north of east on B. On Fig. 1.1, draw an arrow to indicate the approximate direction of the resultant of these two forces.
Show that the resultant force on B has magnitude $6.6\,\text{N}$.
Calculate the magnitude of the acceleration of B caused by this resultant force.
Determine the angle between the acceleration direction and the direction of the $7.5\,\text{N}$ force.