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3 years ago

Which body exerts the force that propels the sprinter, the blocks or the sprinter?

1 answer:

5 0

Answer: The blocks

Explanation:
When the sprinter takes off, he/she presses hard on the block.
The blocks apply an equal and opposite force to the sprinter according to Newton's 3rd law of motion.
The reaction force from the blocks gives the sprinter the initial acceleration to begin the race.

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Experimenting with free fall, Mariana observes that her baseball takes 1.5 s to travel the last 30m before hitting the ground. F

Art [367]

Answer:

37.8 m

Explanation:

At point 0, the ball is at height y₀.

At point 1, the ball is at height 30 m.

At point 2, the ball is at height 0 m.

Given:

y₁ = 30 m

y₂ = 0 m

v₀ = 0 m/s

a = -10 m/s²

t₂ − t₁ = 1.5 s

Find: y₀

Use constant acceleration equation.

y = y₀ + v₀ t + ½ at²

Evaluate at point 1.

y₁ = y₀ + v₀ t₁ + ½ at₁²

30 m = y₀ + (0 m/s) t₁ + ½ (-10 m/s²) t₁²

30 = y₀ − 5t₁²

Evaluate at point 2.

y₂ = y₀ + v₀ t₂ + ½ at₂²

0 m = y₀ + (0 m/s) t₂ + ½ (-10 m/s²) t₂²

0 = y₀ − 5t₂²

y₀ = 5t₂²

Substitute:

y₀ = 5 (1.5 + t₁)²

y₀ = 5 (2.25 + 3t₁ + t₁²)

y₀ = 11.25 + 15t₁ + 5t₁²

30 = 11.25 + 15t₁ + 5t₁² − 5t₁²

30 = 11.25 + 15t₁

t₁ = 1.25

30 = y₀ − 5t₁²

30 = y₀ − 5(1.25)²

y₀ ≈ 37.8

4 0

4 years ago

Explain ALL THREE of Newton’s Laws in your own words.

Svet_ta [14]

Explanation:

(1) Every object moves in a straight line unless acted upon by a force. (2) The acceleration of an object is directly proportional to the net force exerted and inversely proportional to the object's mass. (3) For every action, there is an equal and opposite reaction.

5 0

3 years ago

If an athlete leaps vertically at 4.0m/s, what maximum height does he reach?

joja [24]

Hello
This is a problem of accelerated motion, where the acceleration involved is the gravitational acceleration: $g=-9.81~m/s^2$ , and where the negative sign means it points downwards, against the direction of the motion.

Therefore, we can use the following formula to solve the problem:
$v_f^2 = v_i^2 + 2gS$
where $v_i=4~m/s$ is the initial vertical velocity of the athlete, $v_f=0$ is the vertical velocity of the athlete at the maximum height (and $v_f=0~m/s$ at maximum height of an accelerated motion) and S is the distance covered between the initial and final moment (i.e., it is the maximum height). Re-arranging the equation, we get
$S= \frac{v_f^2-v_i^2}{2g}=0.82~m$

3 0

3 years ago

PLEASE I NEED SOME HELP!

vagabundo [1.1K]

Ill answer the question hold on just a sec

3 0

3 years ago

What is the index of refraction of the second medium if a ray that makes an angle 45.0° in Flint Glass (n=1.65) makes an angle o

Aleonysh [2.5K]

ANSWER:

2nd option: 1.77

STEP-BY-STEP EXPLANATION:

Given:

Angle medium 1 = 45°

Angle medium 2 = 41.3°

n medium 1 = 1.65

We can determine the index of refraction of the second medium using the following formula:

$\begin{gathered} n_1\cdot\sin\theta_1=n_2\cdot\sin\theta_2 \\ \\ \text{ We replacing} \\ \\ \:1.65\cdot\sin45\degree=n_2\cdot\sin41.3°\:\: \\ \\ n_2=\frac{1.65\cdot\sin45\degree}{\sin41.3\degree} \\ \\ n_2=1.77 \end{gathered}$

The index of refraction the new medium is equal to 1.77

Therefore, the correct answer is 2nd option: 1.77

6 0

1 year ago