Answer
Any force greater 490N
Explanation
The force required just to make an object slide over a rough horizontal surface is any force greater that the static friction which given by;
Given;
Hence;
F = 0.5 x 100 x 9.8
F = 490N.
We will only need the coefficient of kinetic friction if we were asked to find the force required to keep the object moving uniformly. Usually, the force needed to keep an object moving uniformly over a rough surface is lesser that which is needed to start its motion.
In this problem, we were only asked to find the minimum force required to make the object move which we have done.
Answer: D
Wavelength λ = 7.5 × 10^-11 m
Explanation:
You are given the frequency of an electromagnetic wave to be:
F = 4.0 x 1018 Hz. And the speed of light C to be
C = 3 × 10^8 m/s
From wave speed formula:
Wave speed is the product of waves frequency and wavelength. That is,
V = fλ
Where
f = frequency
λ = wavelength
V = C = speed of light
Substitute the values of the parameters into the formula
C = fλ
3 × 10^8 = 4 × 10^18 × λ
Make λ the subject of formula
λ = (3×10^8)/(4×10^18)
λ = 7.5 × 10^-11 m
Therefore, the wavelength of the wave is 7.5 × 10^-11 m
Bohr’s model showed that electron orbits had distinct radii.
D. Interaction between a magnetic South Pole and a copper bar
