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4 years ago

When a rock thrown straight up reaches its maximum height, its velocity is?

1 answer:

3 0

Using kinematic equation,
V² - U² = -2ah (minus g is in downward direction)
At highest point, final velocity will be zero. i.e V = 0.
∴ -U² = -2ah
U = √2gh (where a = g and h = maximum height achieved)

You can find velocity if h is given to you.

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a police officer parked on the side of the rode clockes a driver at a constant 130km/h (passing the stopped car). if the officer

nignag [31]

Answer

given,

speed of the vehicle = 130 Km/h

officers accelerates at = 12 km/h/s

time taken by the driver to catch the vehicle = ?

at time t second

$130 t = \dfrac{1}{2}at^2$

$260 t - 12 t^2 = 0$

t (12 t - 260 )= 0

12 t = 260

t = 21.67 s

v = u + at

v = 12 × 21.67

v = 260 Km/h

8 0

4 years ago

g You are blowing air into a spherical balloon at a rate of 33 cubic inches per second. Given that the radius of the balloon is

Marina CMI [18]

Answer:

$\frac{3}{16\pi}in/sec$

Explanation:

We are given that

$\frac{dv}{dt}=3in^3/s$

r=2 in when t=4 s

We have to find the rate of change of radius.

We know that

Volume of sphere= $V=\frac{4}{3}\pi r^3$

Differentiate w.r.t t

$\frac{dV}{dt}=4\pi r^2\frac{dr}{dt}$

Substitute the values

$3=4\pi(2)^2\times \frac{dr}{dt}$

$\frac{dr}{dt}=\frac{3}{4\pi(2)^2}$

$\frac{dr}{dt}=\frac{3}{16\pi}in/sec$

8 0

3 years ago

A rocket moves through outer space at 11,000 m/s. At this rate, how much time would be required to travel the distance from Eart

VladimirAG [237]

Speed = 11000 m/s = 11km/s

D = 380000 km,

t = D/s = 380000 km/ 11km/s

t = 34 545.45 seconds.

4 0

3 years ago

Define the following words:

qwelly [4]

Taxonomy: the techniques of describing,naming and classifying living organisms on the basis of similarities and dissimilarities

Prokaryote: prokaryotes were the earliest living organisms which are unicellular having a primitive nucleus i.e they don’t have a true nucleus

Virus: viruses are non cellular parasitic entities. They cannot live or reproduce outside of living cells since they lack machinery to do so by themselves. They range in size from 20nm to 250nm

7 0

3 years ago

The acrylic plastic rod is 20 mm long and 15 mm in diameter. If an axial load of 300 N is applied to it, determine the change in

Alecsey [184]

Given Information:

diameter = d = 15 mm

Length = L = 20 mm

Axial load = P = 300 N

Eₚ = 2.70x10⁹ Pa

vₚ = 0.4

Required Information:

Change in length = ?

Change in diameter = ?

Answer:

Change in length = 0.01257 mm

Change in diameter = -0.003772 mm

Explanation:

Stress is given by

σ = P/A

Where P is axial load and A is the area of the cross-section

A = 0.25πd²

A = 0.25π(0.015)²

A = 0.000176 m²

σ = 300/0.000176

σ = 1697792.8 Pa

The longitudinal stress is given by

εlong = σ/Eₚ

εlong = 1697792.8/2.70x10⁹

εlong = 0.0006288 mm/mm

The change in length can be found by using

δ = εlong*L

δ = 0.0006288*20

δ = 0.01257 mm

The lateral stress is given by

εlat = -vₚ*εlong

εlat = -0.4*0.0006288

εlat = -0.0002515 mm/mm

The change in diameter can be found by using

Δd = εlat*d

Δd = -0.0002515*15

Δd = -0.003772 mm

Therefore, the change in length is 0.01257 mm and the change in diameter is -0.003772 mm

7 0

3 years ago