Answer:
The speed of the ball is 42.5 m/s
Explanation:
The initial kinetic energy of the ball is:
= 85.75 J
The speed of the ball after leaving the bat is:
V=47.92 m/s
Using kinematic equation we can find the speed of the ball after being 25 m above the point of collision:
Answer:
Explanation:
The centripetal force acting on the car must be equal to mv²/R, where m is the mass of the car, v its speed and R the radius of the curve. Since the only force acting on the car that is in the direction of the center of the circle is the frictional force, we have by the Newton's Second Law:
But we know that:
And the normal force is given by the sum of the forces in the vertical direction:
Finally, we have:
So, the minimum value for the coefficient of friction is 0.27.
Answer:
301.48 J/s
Explanation:
We are given;
Temperature of the sky dropping to −40∘C: T_o = -40°C = -40 + 273 = 233 K
Temperature of your skin and clothes: T = 30°C = 30 + 273 = 303 K
Body surface area of human body is around 2 m². But here only half of the body is facing the sky, Thus Area is: A = 2/2 = 1 m²
To solve this, we will use the equation for thermal heat transfer known as the Stefan bolt Mann equation.
ΔQ/Δt = εσA(T⁴ - (T_o)⁴)
Where;
ΔQ/Δt is the rate at which you body loses energy by radiation
ε is the emissivity of the human body with a value of 0.97
σ is Stefan boltzmann constant with a value of 5.67 X 10^(-8) W/m².K⁴
Thus;
ΔQ/Δt = 0.97 × 5.67 X 10^(-8) × 1(303⁴ - 233⁴)
ΔQ/Δt = 301.48 J/s
Answer: D. Albedo
Explanation:
The proportion of total light incident on surface that is reflected back is called its albedo. These are typical features of an astronomical body. It is a dimension less quantity and its value ranges from 0 to 1. Light surfaces reflect larger amount of light than dark surfaces. This feature can be clearly seen on planet Mars and the Moon.
Thus, the fraction of the total radiation that is reflected by any surface is called its <u>Albedo.</u>