Answers:
a) 222.22 m/s
b) 800.00 km/h
Explanation:
The speed of a wave is given by the following equation:
Where:
is the speed
is the frequency, which has an inverse relation with the period 
is the wavelength
Solving with the given units:
This is the speed of the wave in km/h
Transforming this speed to m/s:

This is the speed of the wave in m/s
Answer:
(a)
(b) 
Solution:
As per the question:
Side of the cube, a = 4.4 cm
Coordinates of the diagonally opposite corner, A = <4.4, 4.4, 4.4> cm
Now,
(a) To calculate the unit vector:
(b) To calculate the angle between the two vectors say A and A' is given by:
(1)
Now,
The coordinates of the diagonally opposite corner, A' is <0, 0, 1> cm
Thus
Now,
Using equation (1) :


Thus


Answer:
The force must he apply to the sled is of F= 764.4 N.
Explanation:
m= 60 kg
g= 9.8 m/s²
μ=0.3
W= m*g
W= 588 N
Fr= μ*W
Fr= 176.4 N
F= W + Fr
F= 764.4 N