Answer:
Magnitude of the Frictional force = (mv₀²)/2x₁
Explanation:
For the frictional force to stop the box, it has to produce the deceleration of the box; thereby being the opposing force to the box's motion.
According to Newton's first law of motion
Frictional force = (mass of the box) × (deceleration experienced by the box)
Let the mass of the box be m
Then,
Frictional force = ma
Then we can obtain the deceleration using the equations of motion
v² = u² + 2ax
u = Initial velocity = v₀ m/s
v = Final velocity = 0 m/s (since the box comes to rest at the end)
x = horizontal distance covered = (x₁ - x₀) = x₁ (since x₀ = 0)
a = ?
v² = u² + 2ax
0 = (v₀)² + 2ax₁
2ax₁ = - v₀²
a = - (v₀²)/(2x₁) (minus sign, because it's a deceleration)
Magnitude of the Frictional force = ma = (mv₀²)/2x₁
When the electric field pierces outward through the section.
<span> (ρ = m / V) hope this helps...:)</span>
#1
As we know that energy of electromagnetic wave is given by

so here we know that penetrating power will directly depends on its energy and energy inversely depends on wavelength
So here we can say correct answer will be
C) The penetrating power decreases as the wavelength increases.
#2
Speed of sound is maximum in solids and minimum in gas
so here as ice melts into water the speed of sound must have to decrease
so correct answer will be
D) The speed of sound would decrease because sound travels faster through solids than liquids.
#3
mechanical waves required medium to travel while non mechanical waves do not require any medium to travel
so here correct answer will be
A) sound