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3 years ago

5. Your friend tosses a ball into the air. The equation h = -5ť + 30t +10 models the height,

Physics

1 answer:

Naily [24]3 years ago

4 0

Answer:

6.3s.

Explanation:

The height h is given by:

$h(t)=-5t^2+30t+10$

Setting the height h = 0 and using the quadratic formula to solve for t:

$0=-5t^2+30t+10\\0=t^2-6t-2\\t_1=3-\sqrt{11}= -0.3s\\t_2=3+\sqrt{11}=6.3s$

t₁ is physicly meaningless.

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A tortoise can run with a speed of 0.14 m/s, and a hare can run 20 times as fast. In a race, they both start at the same time, b

Reptile [31]

speed of tortoise is given as v1 = 0.14 m/s

speed of hare is given as v2 = 20*0.14 = 2.8 m/s

now let say the total length of the path is "d"

so the total time taken by the tortoise to cover this

$t = \frac{d}{0.14}$

now given that hare took rest for 1 min

so total time of run for hare is (t - 60)s

so the distance that hare covered is given by

$d - 0.30 = 2.8 * (t - 60)$

now by above two equations

$d - 0.30 = 2.8 * \frac{d}{0.14} - 168$

$168 - 0.30 = (20 - 1)d$

$d = 8.82 m$

and the time t is given by

$t = \frac{8.82}{0.14}$

$t = 63 s$

so part a)

t = 63 s

part b)

d = 8.82 m

4 0

3 years ago

A jet engine gets its thrust by taking in air, heating and compressing it, and

nadya68 [22]

Answer:

$F=ma=20\ Kg\ 400\ m/s^2=8,000\ Nw$

Explanation:

Thrust is known as a reaction force which appears when a system expels or accelerates mass in one specific direction. If we know the acceleration and the mass of the air expelled by the jet engine, we can compute the thrust .

The acceleration is calculated by using the dynamics formula

$\displaystyle a=\frac{v_f-v_o}{t}$

The values are

$v_f=500\ m/s,\ v_o=100\ m/s,\ t=1\ sec$

$\displaystyle a=\frac{500-100}{1}=400\ m/s^2$

The thrust is

$F=ma=20\ Kg\ 400\ m/s^2=8,000\ Nw$

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3 years ago

QUESTION 1<br> 67.2 kilometers = how many decameters

den301095 [7]

Answer: the answer should be 6,720 decameters.

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3 years ago

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a car travels at 15 m/s for 10 s. It then speeds up with a constant acceleration of 2.0 m/s? for 15 s. At the end of this time,

Firlakuza [10]

V = u + at where u is initial velocity (15 m/s), a is acceleration (2m/s^2) and t is time (15 seconds)

V = 15 + 2 X 15

V = 45 m/s

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3 years ago

Which of the following is not an element of installment credit?

Alex787 [66]

Answer:

c line of credit I believe

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3 years ago