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
Answer:
C. The voltage drop across the resistor is 2.1V and nothing about the current through the resistor.
Explanation:
When connected in parallel, voltage across the resistances are the same. So if 2.1V was dropped across the LED then 2.1V was also dropped across the resistor. However, this tells us nothing about the current through the resistor. We can find the current across the resistor if we know the resistance of the resistor, but that's about it.
If it were a series connection, then the current would have been the same, but the voltage drop were another story.
Answer:
The human ear is most sensitive to sounds in the range of 2000 to 3000 Hz
Acceleration = (change in speed) / (time for the change)
change in speed = (speed at the end) minus (speed at the beginning)
change in speed = (zero) minus (28 m/s) = -28 m/s
Acceleration = (-28 m/s) / (13 sec)
Acceleration = -2.15 m/s²
