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7nadin3 [17]
3 years ago
8

A quarterback throws a football 40 yards in 4 seconds.what is the average speed the football

Physics
2 answers:
lions [1.4K]3 years ago
8 0
The answer is 10 yards per second

almond37 [142]3 years ago
5 0
You just calculate the speed by dividing the distance by the time:
40 yd ÷ 4 sec  = 10 yards per second
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Which of the following is not a synthesis reaction?
Nastasia [14]
C is the awnser because c is single replacement
6 0
3 years ago
You are on a 4 m high ladder and throw a ball upwards at 12 m/s. It lands on the ground below the ladder.
Gelneren [198K]

a) 2.75 s

The vertical position of the ball at time t is given by the equation

y= h+ut-\frac{1}{2}gt^2

where

h = 4 m is the initial height of the ball

u = 12 m/s is the initial velocity of the ball (upward)

g = 9.8 m/s^2 is the acceleration of gravity (downward)

We can find the time t at which the ball reaches the ground by substituting y=0 into the equation:

0 = 4 + 12t - 4.9 t^2

This is a second-order equation. By solving it for t, we find:

t = -0.30 s

t = 2.75 s

The first solution is negative, so we discard it; the second solution, t = 2.75 s, is the one we are looking for.

b) -15.0 m/s (downward)

The final velocity of the ball can be calculated by using the equation:

v=u-gt

where

u = 12 m/s is the initial (upward) velocity

g = 9.8 m/s^2 is the acceleration of gravity (downward)

t is the time

By subsisuting t = 2.75 s, we find the velocity of the ball as it reaches the ground:

v=12 -(9.8)(2.75)=-15.0 m/s

And the negative sign means the direction is downward.

7 0
3 years ago
You toss a rock up vertically at an initial speed of 39 feet per second and release it at an initial height of 6 feet. The rock
3241004551 [841]

Answer:

2.583 s, 29.77 ft and 1.219 s

Explanation:

Using equation of motion and taken the motion upward as positive, also a = g ( acceleration due to gravity) = - 32 fts⁻², V= 39 fts⁻¹ V₁ is final velocity, y is the distance in ft from the ground

H = 6 ft, the height from which it is tossed

V₁ = V + gt = V - gt

at maximum height the body came to rest momentarily V₁ = 0

0 = V - gt

-V = -gt

- 39 / -32 = t

t time to reach maximum height = 1.219 s

To Maximum height reached can be calculated with the formula

V₁² = V² + 2g( y - H) where H is the initial height reached by the tossed rock

where V₁ is the final velocity at maximum height which = 0

0 = V² - 2g(y-H) where y is the distance traveled from the ground

-V² = -2g(y-H)

₋V² / -2g = y-H

(V²/2g) + H = y in ft

(39² / (2 × 32)) + 6

y = 29.77 ft

The total time it will be in air can be calculated with the formula below

y = H + Vt - 0.5gt² from y-H = ut + 0.5at²

0.5gt² - Vt - H = 0 since the body returned to the ground ( y = 0)

0.5gt² - Vt - H = 0

using quadratic formula

- (-V)² ± √ ((-V²) - 4 × 0.5g × -H) / (2 × 0.5 × g)

(V ± √ (V² + 2gH)) ÷ g

substitute the values into the expression

t = (39 + √(39² + (2×-32× 6)))/ 32 or (39 - √ (39² + (2 × -32×6))/ 32

t = (39 + √(1521 +384))/32 = (39 + √1905) / 32  = 2.583 s

t = (39 - √1905) / 32 =  -0.15 s

The will remain in air (V ± √ (V² + 2gH)) / g seconds. It will reach a maximum height of (V²/2g) + H feet after V/g seconds

8 0
3 years ago
You drop a batitin a stationary elevator and the ball hits the floor in o 50 s. How long does it take for the ball to hit the fl
solmaris [256]

Answer:

option (a) 0.61 s

Explanation:

Given;

Time taken by the ball to reach the ground  = 0.50 s

Let us first calculate the distance through which the ball falls on the ground

from the Newton's equation of motion, we have

s=ut+\frac{1}{2}at^2

where,  

s is the distance

a is the acceleration

t is the time

here it is the case of free fall

thus, a = g = acceleration due to gravity

u =  initial speed of the ball = 0

on substituting the values, we get

s=0\times 0.50+\frac{1}{2}\times9.8\times0.50^2

or

s = 1.225 m

Now,

when the elevator is moving up with speed of 1.0 m/s

the initial speed of the ball = -1.0 m/s   (as the elevator is moving in upward direction)

thus , we have

s=ut+\frac{1}{2}at^2

or

1.225=-1.0\times\ t+\frac{1}{2}\times9.8t^2

or

4.9t^2 - t  - 1.225 = 0

or

t = 0.612 s

hence, the correct answer is option (a) 0.61 s

4 0
3 years ago
A cool down is considered the activity performed
tangare [24]

did you mean what activities are performed during the cool down?

5 0
3 years ago
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