contestada

1. A baseball is thrown horizontally at 45 m/s. The ball slows down at a rate of 5 m/s?


a. How long is the ball in the air before coming to rest?


b. How far did the ball travel in that time?


2. A car starts from rest and accelerates at 9.54 m/s? for 6.5 seconds.


a. How much distance was covered by the car?


b. What was the final velocity of the car?


3. An arrow leaves a bow with a speed of 42 m/s. Its velocity is reduced to 34 m/s by the time it

hits its target


a. What was the acceleration of the arrow?


b. How much distance did the arrow travel over if it were in the air for 2.4 seconds?


c. What was the average velocity of the arrow?


4. A ball starts from rest and rolls down a hill with a constant acceleration of 3.0 m/s?.


a. What is its speed at the end of 4.0 s?


b. How far did the ball move in that 4.0 s?

Respuesta :

Answer:

Explanation:

a )

initial velocity u = 45 m/s

acceleration a = - 5 m/s²

final velocity v = 0

v = u - at

0 = 45 - 5 t

t = 9 s

b )

s = ut - 1/2 at²

= 45 x 9 - .5 x5x 9²

405 - 202.5

202.5 m

2 )

a )

s = ut + 1/2 a t²

u = 0

s = 1/2 at²

= .5 x 9.54 x 6.5²

= 201.5 m

b )

v = u + at

= 0 + 9.54 x 6.5

= 62.01 m / s

3

a )

acceleration = (v - u) / t

= (34 - 42) / 2.4

= - 3.33 m /s²

b )

v² = u² - 2 a s

34² = 42² - 2 x 3.33² s

s = 27.41 m

c )

Average velocity

Total displacement / time

= 27.41 / 2.4

= 11.42 m /s

4 )

a )

v = u + at

v = 0 + 3 x 4

= 12 m /s

b )

s = ut + 1/2 a t²

= o + .5 x 3 x 4²

= 24 m

Otras preguntas