a.

30°

b.

45°

c.

60°

d.

90°

a.

wavelength

b.

period

c.

frequency

d.

amplitude

a.

When accelerating, the resultant force acting on it must be equal to zero

b.

There must always be a non zero force acting on it

c.

At a steady velocity, the resultant force acting on it must be equal to zero

d.

At a steady velocity, the air resistance must be equal to zero

a.

volume

b.

mass

c.

thickness

d.

density