Answer:
19.2 m/s
Explanation:
The train is moving at 18 m/s and you are walking in the same direction (east) so the speeds are added
18 + 1.2 = 19.2
If you were walking backwards (west) your velocity with respect to the ground would be
18 - 1.2 = 16.8
Using the formula: ΔY = V₀y * t + (1/2) * ay * t²
Solve for time and get: 1.968s
Then use: v = d/t in the x-direction and get: d = 3.936
Answer:
49 N
Explanation:
In order to move the box at constant speed, the acceleration of the box must be zero (a=0): this means, according to Newton's second law,
F = ma
that the net force acting on the box, F, must be zero as well.
Here there are two forces acting on the box in the horizontal direction while it is moving:
- The force of push applied by the guy, F
- The frictional force, 
For an object moving on a flat surface, the frictional force is given by

where
is the coefficient of friction
m is the mass of the box
g is the acceleration of gravity
So the equation of the forces becomes

And substituting:

We find the force that must be applied by the guy:

Answer:
344.8 Hz
Explanation:
The frequency of a wave is given by:

where
v is the speed of the wave
is its wavelength
Here we have
v = 793 m/s

Substituting into the equation, we find
