a)
Y₀ = initial position of the stone at the time of launch = 0 m
Y = final position of stone = 20.0 meters
a = acceleration = - 9.8 m/s²
v₀ = initial speed of stone at the time of launch = 30.0 m/s
v = final speed = ?
Using the equation
v² = v₀² + 2 a (Y - Y₀)
inserting the values
v² = 30² + 2 (- 9.8) (20 - 0)
v = 22.5 m/s
b)
Y₀ = initial position of the stone at the time of launch = 0 m
Y = maximum height gained
a = acceleration = - 9.8 m/s²
v₀ = initial speed of stone at the time of launch = 30.0 m/s
v = final speed = 0 m/s
Using the equation
v² = v₀² + 2 a (Y - Y₀)
inserting the values
0² = 30² + 2 (- 9.8) (Y - 0)
Y = 46 m
(1 cal/g °C) x (4000 g) x (45 - 25)°C = 80000 cal = 80 kcal. So the answer is 80 kcal .
The distance covered by an object accelerating from rest is
D = (1/2) · (acceleration) · (time)² .
In this particular case, 'acceleration' is 9.8 m/s² ... due to gravity.
D = (1/2) · (9.8 m/s²) · (1.67 s)²
D = (4.9 m/s²) · (2.789 s²)
D = 13.67 meters
Answer: 
Explanation:
Acceleration 
is expressed in the following formula:
Where:
is the final velocity of the projectile
is the initial velocity of the projectile
is the time
Solving:
This is the acceleration of the projectile
Light from other stars take longer to reach the earth because they are farther than our sun.
