The answer is C) A girl hangs by both hands, motionless, from a trapeze.
Question is from B to C
Answer: (b) 1.5m/s
x1=3m, x2=9m
t1=1s, t2=5s
Displacement, ∆x=(9-3)m=6m
Time elapsed, ∆t=(5-1)s=4s
So average velocity v =∆x/∆t=6/4=1.5m/s
Correct choices are marked in bold:
travel in straight lines and can bounce off surfaces --> TRUE, normally electromagnetic waves travel in straight lines, however they can be reflected by objects, bouncing off their surfaces
travel through space at the speed of light --> TRUE, all electromagnetic waves in space (vacuum) travel at the speed of light,
)
travel only through matter --> FALSE; electromagnetic waves can also travel through vacuum
travel only through space --> FALSE, electromagnetic waves can also travel through matter
can bend around objects --> TRUE, this is what happens for instance when diffraction occurs: electromagnetic waves are bended around obstacles or small slits
move by particles bumping into each other --> FALSE, electromagnetic waves are oscillations of electric and magnetic fields, so no particles are involved
move by the interaction between an electric field and a magnetic field --> TRUE, electromagnetic waves consist of an electric field and a magnetic field oscillating in a direction perpendicular to the direction of motion of the wave
Use the Pythagoras for the magnitude and the tan^-1 x = -1 for the angle
displacement = 4^2 + 4^2 = 32 = 4 sqrt(2) = 5.65 km
angle is 135 degrees.