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grin007 [14]
2 years ago
8

A basketball player jumps straight upward. After 0.625 s, she is 0.411 m above the ground. What was her initial velocity? PLEASE

HELP
 use the formula
trianglex = vi * t+ 1/2g * t^2
Physics
1 answer:
Ivahew [28]2 years ago
8 0
Formula for the height is:
h = v i · t - 1/2 g · t²    ( minus sign because the gravitational force is in the opposite direction then the force that a player exerts )
0.411 = v i · 0.625 - 1/2 · 9.81 · 0.625²
0.411 = 0.625 v i - 1.916
0.625 v i = 0.411 + 1.916
0.625 v i = 2.327
v i = 2.327 : 0.625 = 3.72 m /s
Answer: Her initial velocity was 3.72 m/s.
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A Turtle and a Snail are 360 meters apart, and they start to move towards each other at 3 p.m. If the Turtle is 11 times as fast
Neko [114]

Answer:

Snail's speed = \frac{30m}{2400s} = 0.0125m/s

Turtle's speed =  \frac{330m}{2400s} = 0.1375m/s

Explanation:

Let the snail's speed be x m/s

The turtle's speed then is 11x m/s

Speed = Distance ÷ Time

Since speed and distance are directly proportional;

The ratio of the distances snail and turtle cover before they meet is x:11x respectively.

Simplified, the ratio of snail distance : turtle distance = 1:11

So snail covers a distance of \frac{1}{12} × 360 = 30m

And turtle covers a distance of \frac{11}{12} × 360 = 330m

The time each took before they met is 40 × 60 = 2400 seconds

Snail's speed = \frac{30m}{2400s} = 0.0125m/s

Turtle's speed =  \frac{330m}{2400s} = 0.1375m/s

8 0
2 years ago
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A system delivers 1275 j of heat while the surroundings perform 855 j of work on it. calculate ∆esys in j.
kakasveta [241]
The first law of thermodynamics says that the variation of internal energy of a system is given by:
\Delta U = Q + W
where Q is the heat delivered by the system, while W is the work done on the system.

We must be careful with the signs here. The sign convention generally used is:
Q positive = Q absorbed by the system
Q negative = Q delivered by the system
W positive = W done on the system
W negative = W done by the system

So, in our problem, the heat is negative because it is releaed by the system: 
Q=-1275 J
while the work is positive because it is performed by the surrounding on the system:
W=+855 J

So, the variation of internal energy of the system is
\Delta U = -1275 J+855 J=-420 J
6 0
2 years ago
You are driving to the grocery store at 20 m/s. You are 110m from an intersection when the traffic light turns red. Assume that
oksano4ka [1.4K]

As we know that reaction time will be

t = 0.50 s

so the distance moved by car in reaction time

d = vt

d = 20 \times 0.50

d = 10 m

now the distance remain after that from intersection point is given by

d = 110 - 10 = 100 m

So our distance from the intersection will be 100 m when we apply brakes

now this distance should be covered till the car will stop

so here we will have

v_f = 0

v_i = 20 m/s

now from kinematics equation we will have

v_f^2 - v_i^2 = 2 a d

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a = \frac{-400}{200} = -2 m/s^2

so the acceleration required by brakes is -2 m/s/s

Now total time taken to stop the car after applying brakes will be given as

v_f - v_i = at

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total time to stop the car is given as

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3 0
2 years ago
Pendulum clocks are made to run at the correct rate by adjusting the pendulum’s length. Suppose you move from one city to anothe
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Answer:

Obviously Lengthen...   T = 2\pi \sqrt{L/g}   or   g = 4\pi ^{2} L/g

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As we can observe from the equation, time period of a simple pendulum depends upon the length directly. When the gravitational acceleration increases the time period of the pendulum decreases and vice versa. So, by increasing the length, the time period can be adjusted...

4 0
2 years ago
The speed of light in a transparent medium is 0.6 times that of its speed in vacuum. Find the refractive index of the medium.
grin007 [14]
<h2>Answer:</h2>

The refractive index is 1.66

<h2>Explanation:</h2>

The speed of light in a transparent medium is 0.6 times that of its speed in vacuum .

Refractive index of medium = speed of light in vacuum / speed of light in medium  

So

RI = 1/0.6 = 5/3 or 1.66

3 0
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