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Katena32 [7]
3 years ago
14

A swimmer bounces straight up from a diving board and falls feet first into a pool. She starts with a velocity of 3.00 m/s, and

her takeoff point is 1.80 m above the pool.(a) How long are her feet in the air?(b) What is the highest point above the board her feet reach? (c) What is her velocity when her feet hit the water?
Physics
1 answer:
Leya [2.2K]3 years ago
4 0

Answer:

A) 0.9844 s

B) x2 = 0.4587 m

C) v = 6.657 m/s

Explanation:

We are given;

Height of take off point above pool; x1 = 1.8 m

Initial take off velocity; u = 3 m/s

Final velocity at highest point before free fall; v = 0 m/s

B) To find the highest point above the board her feet reaches means the distance from take off to the top of the motion just before free fall.

Thus, we will be using equation of motion and we have;

v² = u² + 2gs

Now, let s = x2 which will be the distance between take off and the top before free fall.

So;

v² = u² + 2g(x2)

Now,since the motion is against gravity, g will be negative.

Thus;

v² = u² + 2(-9.81)(x2)

Plugging in the relevant values to give;

0² = 3² - (19.62x2)

19.62(x2) = 9

x2 = 9/19.62

x2 = 0.4587 m

A) We want to find how long her feet is in air.. It means we want to find out the time to get to a distance of x1 and also the time to achieve the distance (x1 + x2) on free-fall.

Thus, using equation of motion;

v = u + gt

Again, g = -9.81

Thus;

0 = 3 - 9.81t1

9.81t1 = 3

t1 = 3/9.81

t1 = 0.3058 s

Now, for the time taken to achieve the distance (x1 + x2) on free-fall, we will use the formula;

s = ut + ½gt²

Where s = (x1 + x2) = 1.8 + 0.4587 = 2.2587 m

And now, u = 0 m/s because the start of the free fall is from maximum height with velocity of 0 m/s. Again, g = - 9.81 m/s²

Thus;

2.2587 = 0 - ½(-9.81)(t2)²

2.2587 = 4.905(t2)²

(t2)² = 2.2587/4.905

(t2)² = 0.4605

t2 = √0.4605

t2 = 0.6786 s

Thus, total time of feet in air = t1 + t2 = 0.3058 + 0.6786 = 0.9844 s

C) Velocity when feet hit the water would be given by;

v = u + gt

Where u = 0 m/s and t = t2 = 0.6786

Since it's in direction of gravity, g = 9.81 m/s

v = 0 + (0.6786 × 9.81)

v = 6.657 m/s

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3 years ago
1)the car's engine power is 44000W. Explain this number in a physical sense
Ratling [72]

Answer:

1) It expresses the rate (top speed) at which it can move with time.

2) P = 20 W

3) h = 18 km

Explanation:

1) Power is the rate of transfer of energy.

⇒ Power = \frac{Energy(or workdone)}{Time}

i.e P = \frac{E}{t}

Thus a car's engine power is 44000W implies that the engine of the car can propel the car at this rate. This expresses the rate (top speed) at which it can move with time.

2) m = 400g = 0.4 kg

    t = 20 s

h = 100m

g = 10 m/s^{2}

P = \frac{mgh}{t}

  = \frac{0.4*10*100}{20}

  = \frac{400}{20}

P = 20 W

3) u = 600 m/s

   g = 10 m/s^{2}

From the third equation of free fall,

V^{2} = U^{2} - 2gh

V is the final velocity, U is the initial velocity, h is the height.

0 = (600)^{2} - 2 x 10 x h

0 = 360000 - 20h

20h = 360000

h = \frac{360000}{20}

  = 18000

h = 18 km

The maximum height of the bullet would be 18 km.

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The seventh planet from the sun is Uranus.

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What is an ion and how does an atom become both positive or negative ion?
Bess [88]

Answer:

An ion is an atom or group of atoms with a positive or negative charge. Ions form when atoms lose or gain electrons to obtain a full outer shell: metal atoms lose electrons to form positively charged ions non-metal atoms gain electrons to form negatively charged ions.

Explanation:

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2 years ago
An 80-kg astronaut becomes separated from his spaceship. He is 15.0 m away from it and at rest relative to it. In an effort to g
9966 [12]

The astronaut will take 300 seconds

Explanation:

We can solve this problem by using the law of conservation of momentum.

In fact, the total momentum of the astronaut+object system must be conserved.

Initially, they are both at rest, so their total momentum is zero:

p=0

After the astronaut throws the object, their total momentum is:

p=MV+mv

where:

M = 80 kg is the mass of the astronaut

V is the final velocity of the astronaut

m = 500 g = 0.5 kg is the mass of the object

v = 8.0 m/s is the velocity of the object

Since momentum is conserved, we can write

0=MV+mv

And solving for V,

V=-\frac{mv}{M}=-\frac{(0.5)(8.0)}{80}=-0.05 m/s

Which means that he starts moving at 0.05 m/s in the direction opposite to the object.

Now the astronaut needs to cover a distance of

d = 15.0 m

And his speed is

v = 0.05 m/s

Therefore, the time taken is

t=\frac{d}{v}=\frac{15.0}{0.05}=300 s

Learn more about momentum here:

brainly.com/question/7973509

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brainly.com/question/2370982

brainly.com/question/9484203

#LearnwithBrainly

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