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PtichkaEL [24]
3 years ago
12

A tennis player standing 12.6m from the net hits the ball at 3.00 degrees above the horizontal. To clear the net, the ball must

rise at least 0.330m. If the ball just clears the net at the apex of its trajectory, how fast was the ball moving when it left the racket? Please show wooooorkkkkk =)
Physics
2 answers:
mezya [45]3 years ago
4 0
We actually don't need to know how far he/she is standing from the net, as we know that the ball reaches its maximum height (vertex) at the net. At the vertex, it's vertical velocity is 0, since it has stopped moving up and is about to come back down, and its displacement is 0.33m. So we use v² = u² + 2as (neat trick I discovered just then for typing the squared sign: hold down alt and type 0178 on ur numpad wtih numlock on!!!) ANYWAY....... We apply v² = u² + 2as in the y direction only. Ignore x direction. 
IN Y DIRECTION: v² = u² + 2as 0 = u² - 2gh u = √(2gh) (Sub in values at the very end) 
So that will be the velocity in the y direction only. But we're given the angle at which the ball is hit (3° to the horizontal). So to find the velocity (sum of the velocity in x and y direction on impact) we can use: sin 3° = opposite/hypotenuse = (velocity in y direction only) / (velocity) So rearranging, velocity = (velocity in y direction only) / sin 3° = √(2gh)/sin 3° = (√(2 x 9.8 x 0.33)) / sin 3° = 49 m/s at 3° to the horizontal (2 sig figs)
NemiM [27]3 years ago
3 0

Answer:

48.6 m/s

Explanation:

height, h = 0.33 m

angle of projection, θ = 3°

Let the velocity of projection is u.

Use the formula for the maximum height raised

H=\frac{u^{2}Sin^{2}\theta }{2g}

0.33=\frac{u^{2}Sin^{2}3 }{2\times 9.8}

u = 48.6 m/s

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What other structures is it near hypothalamus?
Colt1911 [192]
The other structures near the hypothalamus are thalamus and the pituitary gland. 
Hypothalamus is located below the thalamus and is part of the limbic system. It is an integral part of the brain, it is a small cone-shaped structure that projects down ward from the brain, ending in the pituitary stalk, a tubular connection to the pituitary gland. 
3 0
3 years ago
An athlete swings a ball, connected to the end of a chain, in a horizontal circle. The athlete is able to rotate the ball at the
Andrei [34K]

Answer:

a) 2nd case rate of rotation gives the greater speed for the ball

b) 1534.98 m/s^2

c) 1515.04 m/s^2

Explanation:

(a) v = ωR

when R = 0.60, ω = 8.05×2π

v = 0.60×8.05×2π = 30.34 m/s

Now in 2nd case

when R = 0.90, ω = 6.53×2π

v = 0.90×6.53×2π = 36.92 m/s

6.35 rev/s gives greater speed for the ball.

(b) a = ω^2 R = (8.05×2π)^2 )(0.60) = 1534.98 m/s^2

(c) a = ω^2 R = (6.53×2π)^2 )(0.90) = 1515.05 m/s^2

7 0
3 years ago
A metal container with the oil weigh
MA_775_DIABLO [31]

Answer:

16 kg

Explanation:

M - container

m - oil mass

by definition of density ,

relative density is the ratio of the density of a substance to the density of water.

relative density = density/ density of water

density of oil = 1.2*1000 kgm⁻³  = 1200 kgm⁻³

1 Litre =10⁻³ m³

oil volume = 80 *10⁻³ m³

mass of oil = density * volume

                   = 1200*80*10⁻³

                   = 96 kg

Mass of container + mass of  oil =112

mass of container = 112 - 96

                              = 16 kg

7 0
3 years ago
You stand on a frictional platform that is rotating at 1.8 rev/s. Your arms are outstretched, and you hold a heavy weight in eac
dusya [7]

Answer:

20.62361 rad/s

489.81804 J

Explanation:

I_i = Initial moment of inertia = 9.3 kgm²

I_f = Final moment of inertia = 5.1 kgm²

\omega_i = Initial angular speed = 1.8 rev/s

\omega_f = Final angular speed

As the angular momentum of the system is conserved

I_i\omega_i=I_f\omega_f\\\Rightarrow \omega_f=\dfrac{I_i\omega_i}{I_f}\\\Rightarrow \omega_f=\dfrac{9.3\times 1.8}{5.1}\\\Rightarrow \omega_f=3.28235\ rev/s=3.28235\times 2\pi=20.62361\ rad/s

The resulting angular speed of the platform is 20.62361 rad/s

Change in kinetic energy is given by

\Delta K=\dfrac{1}{2}(I_f\omega_f^2-I_i\omega_i^2)\\\Rightarrow \Delta K=\dfrac{1}{2}(5.1\times (20.62361)^2-9.3\times (1.8\times 2\pi)^2)\\\Rightarrow \Delta K=489.81804\ J

The change in kinetic energy of the system is 489.81804 J

As the work was done to move the weight in there was an increase in kinetic energy

6 0
3 years ago
C
Angelina_Jolie [31]
I am very sorry I don’t know
7 0
3 years ago
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