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2 years ago

A kickoff sends a football with an initial velocity of 25 m/s at an angle of 50

Physics

1 answer:

eduard2 years ago

7 0

Answer:

The x-component of the velocity is 16.07 m/s

The y-component of the velocity is 19.15 m/s

Explanation:

Given;

initial velocity of the football, u = 25 m/s

angle of projection, θ = 50⁰

The x-component of the velocity (horizontal component) is given as;

$V_x = Vcos(50^0)\\\\V_x = 25 \ m/s \ \ \times \ \ 0.6428\\\\V_x = 16.07 \ m/s$

The y-component of the velocity (vertical component) is given as;

$V_y = Vsin(50^0)\\\\V_y = 25 \ m/s \ \ \times \ \ 0.766\\\\V_y = 19.15 \ m/s$

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A 20.0-N weight slides down a rough inclined plane which makes an angle of 30 degree with the horizontal. The weight starts from

Ulleksa [173]

Answer:

$1270.64\ \text{J}$

Explanation:

m = Mass of object = $\dfrac{mg}{g}$

mg = Weight of object = 20 N

g = Acceleration due to gravity = $9.81\ \text{m/s}^2$

v = Final velocity = 15 m/s

u = Initial velocity = 0

d = Distance moved by the object = 150 m

$\theta$ = Angle of slope = $30^{\circ}$

f = Force of friction

fd = Work done against friction

The force balance of the system is

$\dfrac{1}{2}m(v^2-u^2)=(mg\sin\theta-f)d\\\Rightarrow \dfrac{1}{2}mv^2=mg\sin\theta d-fd\\\Rightarrow fd=mg\sin\theta d-\dfrac{1}{2}mv^2\\\Rightarrow fd=20\times \sin 30^{\circ}\times 150-\dfrac{1}{2}\times \dfrac{20}{9.81}\times 15^2\\\Rightarrow fd=1270.64\ \text{J}$

The work done against friction is $1270.64\ \text{J}$ .

8 0

3 years ago

The period of a sound wave coming from an instrument is 0. 002 seconds. What is the frequency of the sound? Hz.

Pie

The period is the time taken by the wave to complete an oscillation. The frequency of the given sound is 500 Hz.

<h2>Period:</h2>

It is the time taken by the wave to complete an oscillation. The frequency is inversely proportional to the time:

$f = \dfrac 1T$

Where,

$f$ - frequency

$T$ - period = 0.002 s

Put the value in the equation,

$f = \dfrac 1{0.002}\\\\f = 500\rm \ Hz$

Therefore, the frequency of the given sound is 500 Hz.

Learn more about Period:

brainly.com/question/842349

5 0

2 years ago

A 25 kg bear slides, from rest, 12 m down a lodgepole pine tree, moving with a speed of 5.6 m/s just before hitting the ground.

Anuta_ua [19.1K]

Answer:

(A) -2940 J

(B) 392 J

(C) 212.33 N

Explanation:

mass of bear (m) = 25 kg

height of the pole (h) = 12 m

speed (v) = 5.6 m/s

acceleration due to gravity (g) = 9.8 m/s

(A) change in gravitational potential energy (ΔU) = mg(height at the bottom- height at the top)

height at the bottom = 0

= 25 x 9.8 x (0-12) = -2940 J

(B) kinetic energy of the Bear (KE) = $0.5mv^{2}$

= $0.5 x 25 x 5.6^{2}$ = 392 J

change in KE (ΔKE) = initial KE - final KE
ΔKE = $0.5mv^{2}$ - $0.5mvf^{2}$
when the Bear reaches the bottom of the pole, the final velocity (Vf) is 0, therefore the change in kinetic energy becomes ΔKE = $0.5x25x5.6^{2}$ - 0 = 392 J

\frac{-(ΔKE+ΔU)}{h}[/tex] = $\frac{-(392 + (-2940))}{12}$

= $\frac{(-392 + 2940)}{12}$ = 212.33 N

5 0

3 years ago

In which phase of matter are the atoms closely packed but still able to slide past each other?

borishaifa [10]

The phase of matter is the Solid Phase.

3 0

3 years ago

During an early phase of the planet's existence, earth's atmosphere was similar in composition to the atmospheres of mars and ve

KengaRu [80]

The answer is carbon dioxide. This primordial earths’ atmosphere was composed by gasses from degassing of the earth's interior after its formation. It is after the beginning of life that oxygen levels began to rise and levels of carbon dioxide began to reduce in the atmosphere (as a result of photosynthesis).

8 0

3 years ago