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Tju [1.3M]
3 years ago
7

The rock falls from the distance of 15 m before it hits the water. Calculate its kinetic energy just before hitting the water. S

how your working
Physics
2 answers:
yarga [219]3 years ago
7 0

Answer:

8.57m

Explanation:

v²=u²+2as

then1/2mv²

UkoKoshka [18]3 years ago
6 0

Answer:

k.e =  \frac{1}{2} m {v}^{2}  \\    {v}^{2}  =  {u}^{2}   +  2gs \\  {v}^{2}  = 0  + (2 \times 9.8 \times 15) \\ v = 17.1 \: m {s}^{ - 1}  \\ k.e =  \frac{1}{2}  \times m \times  {17.1}^{2}  \\  = 147m \: joules \\ m \: is \: mass

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Question 9
egoroff_w [7]

Answer:

C

Explanation:

F=ma

given solution

v=12m/s a=v/t

s=6 sec =12m/s÷6sec

=2m/s^2 then we get acceleration now we will find the mass. first derive the the formula of mass by crisis cross then you will get this formula which is m=F/a

=36÷2

= 18

6 0
3 years ago
A sound wave has a speed of 343 m/s in air. What is the wavelength of a sound wave with a frequency of 686 Hz
Svetradugi [14.3K]

Wavelength is the distance between 2 adjacent points in a wave

we can use the following equation to find the wavelength of a sound wave

wavelength = speed / frequency

frequency is the number of waves passing a point in 1 second

substituting the values in the equation

wavelength = 343 m/s / 686 Hz

wavelength = 0.5 m

wavelength of the wave is 0.5 m

6 0
3 years ago
a projectile is launched at an angle of 30 degrees and lands later at the same level. if it's initial speed is 50 m/s, solve for
Mrrafil [7]
using \: the \: formula \\ t = \frac{2u \sin( \alpha ) }{g} where \: u = initial \: speed \: \\ \alpha = angle \: of \: projection \\ g = acceleration \: due \: to \: gravity \\ \frac{2 \times 50 \times \sin(30) }{10} \\ \frac{100 \times 0.5}{10} = \frac{50}{10} = 5seconds

Maximum height
= (Usinα)^2/2g
(50*0.5)^2/20
25^2/20
625/20
=31.25metres
horizontal distance = Range= [U^2 * sin2α]/g
[50^2 * sin60]/10
2500 * 0.8660/10
2165/10=216.5metres
3 0
3 years ago
A uniform cylindrical grindstone has a mass of 10 kg and a radius of 12 cm. (a) What is the rotational kinetic energy of the gri
Drupady [299]

Answer:

a) KE = 888.26J

b) N = 294.5 turns

Explanation:

For the kinetic energy:

KE = I/2*\omega_o^2

The inertia is:

I=m/2*R^2=0.072kg.m^2

So, the kinetic energy will be:

KE = 888.26J

Now, friction force is:

Ff = μ*N = 0.80*5N = 4N

The energy balance would be:

Kf - Ko = Wf    where Kf=0;   Ko = 888.26J;  and Wf is the work done by friction force.

Wf = -Ff*d = -Ff*N*2*π*R   where N is the amount of turns it gives.

Replacing these values into the energy balance:

0-888.26=-4*N*2*π*0.12

-888.26=-0.96*π*N

N=294.5 turns

6 0
3 years ago
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
lyudmila [28]

Answer: Answer to the I'm Tall when I'm Young, and I'm Short when I'm Old. What am I? Riddle is a candle

Hope this helps

7 0
2 years ago
Read 2 more answers
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