word problem

Question

CAN YOU SHOW ME STEP BY STEP? AND SHOW THE EQUATIONS?PLEASEEE!!!

 

some baseball fans believe that pitchers can throw a baseball that rises as it approaches the batter. this seems to contradict common sense, that the ball should fall because of gravity. However, a ball pitched with backspin is subject to a lifting force that acts againsts gravity. the lifting force is about 20% of the force gravity. this means that ball with backspin falls about 80% of distance that a ball without backspin falls.

 

A rising fast ball is an illusion. A ball thrown with backspin may appear to rise simply because it does not fall as much as the batter expects it to. You can confirm this by completing exercises.

 

1. It is about 18.4 m from the picther's mound to home plate. A reasonably fast pitch travels at about 150 km/h. calculate how long it takes the ball to reach at this speed, to the nearest hundredth of a second.

2.Assume that pitcher throws a ball horizontally without backspin.after the ball leaves the pitcher's hand. it begins to fall. From physics, the distance, s metres, that it fall is given by formula s=4.9t², where t is the elapse time seconds. Use your answer to exsercise 1. Determine how far the ball has fallen by time it reaches the batter. give your answer to the nearest centimetre.

3.suppose the ball is thrown with backspin. About how fas would it have fallen by the time it reaches the batter?

Answer 1

1)

We will simply use the formula time = distance / speed here.
Note that within the calculations, I am actually changing the units.
For example 1 km = 1000 m, so I multipied 150 km/h by 1000 to get 150000 m/h.

Time
= Distance / Speed
= 18.4m / (150 km/h)
= 18.4m / (150000 m/h)
= 0.000122666 h
= 0.000122666 * 60 * 60 s
= 0.4416 s
~ 0.44 s

2)

Note that I am just substituting the value of t found in 1) into the equation s = 4.9t^2 given here.
The answer must be in cm, so once again, we need to convert m into cm.

s
= 4.9(0.4416)^2 m
= 0.955551744 m
= 0.955551744 * 100 cm
= 95.5551744 cm
~ 96 cm

3)

In the question, it is mentioned that the distance fallen will only be 80% of the original fallen distance. Thus, we multiply the answer in 2) by 80%.

Distance fallen
= 80% * 95.5551744 cm
= 0.8 * 95.5551744 cm
= 76.44413952 cm
~ 76 cm

Comments

can you send to me the equation?