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2 years ago

Pete is driving down 7th Street. He

Physics

1 answer:

lukranit [14]2 years ago

8 0

Answer:

v=10.75m/s

Explanation:

It is given that,

Pete drives 215 Meters in 20 seconds. He is driving down 7th floor. We need to find his speed.

Speed = distance/time

⇒

$v=\dfrac{215\ m}{20\ s}\\\\v=10.75\ m/s$

Hence, the speed of Pete is 10.75 m/s.

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It takes 275n to set a stationary 77.3 crate in motion. what is the coefficient of static friction?

victus00 [196]

Note: I'm assuming the data 77.3 is the mass of the crate.

Answer:

$\mu_s =0.36$

Explanation:

The coefficient of static friction, called \mu_s is the ratio between the force needed to start moving an object above a rough surface (Fr), and the normal force the surface exerts on the object (N).

$\displaystyle \mu_s =\frac{Fr}{N}$

The normal force is numerical equivalent to the weight of the body if no other external forces are acting.

$N=m\cdot g$

The mass of the crate is m=77.3 Kg, thus its weight and normal force is:

$N=77.3\ kg\cdot 9.8\ m/s^2$

$N= 757.54\ Nw$

Now we calculate the coefficient:

$\displaystyle \mu_s =\frac{275\cancel{N}}{757.54\cancel{N}}$

$\boxed{\mu_s =0.36}$

3 0

2 years ago

If a wind instrument, such as a tuba, has a fundamental frequency of 56.0 Hz, what are its first three overtones (in Hz)? It is

lord [1]

Answer:

168 Hz, 280 Hz and 392 Hz

Explanation:

The resonant frequencies for a closed pipe at one end is given by :

$f=\dfrac{nv}{4L}$ , n = 1,3,5...

The fundamental frequency, f₁ = v/4l = 56 Hz

For first overtone, put n = 3

$f_3=\dfrac{3v}{4L}\\\\=3\times \dfrac{v}{4L}\\\\=3\times 56\\\\=168\ Hz$

For second overtone, put n = 5

$f_5=5\times f_1\\\\=5\times 56\\\\=280\ Hz$

For third overtone, put n = 7

$f_7=7\times f_1\\\\=7\times 56\\\\=392\ Hz$

So, the first three overtones are 168 Hz, 280 Hz and 392 Hz.

3 0

2 years ago

A rock is suspended by a light string. When the rock is in air, the tension in the string is 51.9 N . When the rock is totally i

Luden [163]

Answer:

$\rho _{liquid}=1995.07kg/m^{3}$

Explanation:

When the rock is immersed in unknown liquid the forces that act on it are shown as under

1) Tension T by the string

2) Weight W of the rock

3) Force of buoyancy due to displaced liquid B

For equilibrium we have $T_{3}+B = W_{rock}$

$T_{3}+\rho _{Liquid}V_{rock}g$ = $W_{rock}.....(\alpha)$

When the rock is suspended in air for equilibrium we have

$T_{1}=W_{rock}....(\beta)$

When the rock is suspended in water for equilibrium we have

$T_{2}$ + $\rho _{water}V_{rock}g$ = $W_{rock}.....(\gamma)$

Using the given values of tension and solving α,β,γ simultaneously for $\rho _{Liquid}$ we get

$W_{rock}=51.9N\\31.6+1000\times V_{rock}\times g=51.9N\\\\11.4+\rho _{liquid}V_{rock}g=51.9N\\\\$

Solving for density of liquid we get

$\rho _{liquid}=\frac{51.9-11.4}{51.9-31.6}\times 1000$

$\rho _{liquid}=1995.07kg/m^{3}$

5 0

2 years ago

1. You wish to heat 20 kg of water from 40°C to 80°C. How many kcal of heat are necessary to do this? To how many kJ does this c

adelina 88 [10]

Answer:

Explanation:

Heat energy used up can be calculated using the formula:

H = mcΔt

m = mass oof the object (in kg) = 20kg

c = specific heat capacity of water = 4179.6J/kg°C

Δt change in temperature = 80-40 = 40°C

H= 20* 4179.6 * 40

H = 3,343,680Joules

H = 3,343.68kJ

8 0

2 years ago

A car is moving initially at 30 m/s comes gradually at stop at 900 m . What is acceleration of the car ?

ziro4ka [17]

The acceleration of the car is 0.5 meters per seconds square.

Given the following data:

Initial velocity, U = 30 m/s

Distance, S = 900 meters

Note: The final velocity (V) of the car would be zero (0) m/s when it comes to a stop.

To find the acceleration of the car, we would use the third equation of motion;

Mathematically, the third equation of motion is given by the formula;

$V^2 = U^2 - 2aS\\\\0 = 30^2 - 2a(900)\\\\0 = 900 - 1800a\\\\1800a = 900\\\\a = \frac{900}{1800}$

Acceleration, a = 0.5 $m/s^2$

Therefore, the acceleration of the car is 0.5 meters per seconds square.