C.
The force of friction = coefficient of friction * normal force.
Adding the book to the boy increases the normal force and the component of the gravitational force directed down the slide. This in turn increases the force of friction as can be seen by the relationship from the above equation. For a stationary object, the force of static friction is always equal to the force applied (in this case, it is the component of the gravitational force directed down the slide). That means that so long as the boy is not moving and his mass increases, the frictional force is increasing also to balance the increased downward gravitation force directed down the slide.
It will take the battery 15 hours to discharge completely.
<h3>Energy stored in a battery</h3>
Energy is defined as the ability or capacity to work. The formula for calculating the energy stored in a battery is expressed as;
Energy stored=Power×Time
Energy stored = ΔV * t
where
ΔV is the change in velocity
t is the time
Substitute
Energy stored = 12.0 * 90.0
Energy stored = 1080 W.h
Total power consumed by the headlight = 2 * 36
Total power consumed by the headlight = 72Watts
Determine the time it takes to dischage
Time = Energy Stored/Power
Time = 1080/72
Time = 15hrs
Hence it will take the battery 15 hours to discharge completely.
Learn more on energy consumption here: brainly.com/question/24338873
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Answer:
Vd = 1.597 ×10⁻⁴ m/s
Explanation:
Given: A = 3.90×10⁻⁶ m², I = 6.00 A, ρ = 2.70 g/cm³
To find:
Drift Velocity Vd=?
Solution:
the formula is Vd = I/nqA (n is the number of charge per unit volume)
n = No. of electron in a mole ( Avogadro's No.) / Volume
Volume = Molar mass / density ( molar mass of Al =27 g)
V = 27 g / 2.70 g/cm³ = 10 cm³ = 1 × 10 ⁻⁵ m³
n= (6.02 × 10 ²³) / (1 × 10 ⁻⁵ m³)
n= 6.02 × 10 ²⁸
Now
Vd = (6A) / ( 6.02 × 10 ²⁸ × 1.6 × 10⁻¹⁹ C × 3.9×10⁻⁶ m²)
Vd = 1.597 ×10⁻⁴ m/s
The complete queston is The amount of a radioactive element A at time t is given by the formula
A(t) = A₀e^kt
Answer: A(t) =N e^( -1.2 X 10^-4t)
Explanation:
Given
Half life = 5730 years.
A(t) =A₀e ^kt
such that
A₀/ 2 =A₀e ^kt
Dividing both sides by A₀
1/2 = e ^kt
1/2 = e ^k(5730)
1/2 = e^5730K
In 1/2 = 5730K
k = 1n1/2 / 5730
k = 1n0.5 / 5730
K= -0.00012 = 1.2 X 10^-4
So that expressing N in terms of t, we have
A(t) =A₀e ^kt
A₀ = N
A(t) =N e^ -1.2 X 10^-4t
