Answer:
His acceleration is 
Explanation:
Newton's second law states that acceleration of a body is cause by a net force, the relation between them is:
On the boy there're acting two forces, his weight (W) that points downward and the frictional force (f) that points upward (they boy moves downward and friction always is opposite to movement). So 
so (1) is:
Using the positive direction downward weight and gravitational acceleration(g) are positive and friction force is negative:
, solving for a:
, weight is mg:
U = 0, initial vertical velocity
v = 60 mph = 88 ft/s
Ignore air resistance and take g = 32 ft/s².
It t = time to attain 60 mph, then
(88 ft/s) = (32 ft/s²)*(t s)
t = 88/32 = 2.75 s
Answer: 2.75 s
a. As sun peeks, it creates a straight line- sun to tree to shadow, angle=180°
b. During morning, the sun-tree-shadow changes from 180° to 90°, during noon, angle =90°.During sunset the angle changes from 90 to 0°.
c. Acute angles created in afternoon.
d. A right angle would be created at noon.
e. Obtuse angle would be created in morning.
f. Yes, a straight angle would be created at sunrise.
g. When sun is at mid-morning, the angle=45°+90°= 135°
Falling water that turns a turbine
