Which statement uses power correctly? (1 point)

Determine the magnitude and direction of the resultant velocity of 75.0 m/s. 25.0 east of north, and 100.0 m/s, 25.0 east of sou

aleksandr82 [10.1K]

Answer:

77.35 m / s

Ф = -17° from + X axis or 343° from + X axis

Explanation:

v1 = 75 m/s 25° east of north

v2 = 100 m/s 25° east of south

Write the velocities in vector form ,we get

$\overrightarrow{v_{1}}=75\left ( Sin25\widehat{i} +Cos25\widehat{j}\right )=31.7\widehat{i}+67.97\widehat{j}$

$\overrightarrow{v_{1}}=100\left ( Sin25\widehat{i} -Cos25\widehat{j}\right )=42.26\widehat{i}-90.63\widehat{j}$

Now add the velocity vectors to get the resultant of the velocities.

$\overrightarrow{v}=\overrightarrow{v_{1}}+\overrightarrow{v_{2}}$

$\overrightarrow{v}=\left (31.7+42.26 \right )\widehat{i}+\left ( 67.97- 90.63 \right )\widehat{j}$

$\overrightarrow{v}=73.96\widehat{i}-22.66\widehat{j}$

magnitude of resultant velocity is $\sqrt{\left ( 73.96 \right )^{2}+\left ( -22.66 \right )^{2}}$

= 77.35 m / s

The direction is Ф from X axis

$tan\phi =\frac{-22.66}{73.96}=-0.306$

Ф = -17° from + X axis or 343° from + X axis

7 0

4 years ago

. 1. True False In AM waves, amplitude changes.

Dennis_Churaev [7]

That is true Step by step:

3 0

3 years ago

Read 2 more answers

You need to purchase a motor to supply 400 joules [J] in 10 seconds [s]. All of the motors you can choose from are 80% efficient

kondor19780726 [428]

Answer:

32 W.

Explanation:

Power: This can be defined as the ratio of energy to time. The S.I unit of power is watt(W). The formula for power is given as,

P = W/t.................... Equation 1

Where P = power, W = work done, t = time.

Given: W = 400 J, t = 10 s.

Substitute into equation 1

P = 400/10

P = 40 W.

If the motors that is choose is 80% efficient,

P' = P(0.8)

Where P' = minimum power

P' = 40(0.8)

P' = 32 W.

5 0

3 years ago

A cube of ice at an initial temperature of -15.00°C weighing 12.5 g total is placed in 85.0 g of water at an initial temperature

Leona [35]

Answer: The specific heat of ice is 2.11 J/g°C

Explanation:

When ice is mixed with water, the amount of heat released by water will be equal to the amount of heat absorbed by ice.

$Heat_{\text{absorbed}}=Heat_{\text{released}}$

The equation used to calculate heat released or absorbed follows:

$Q=m\times c\times \Delta T=m\times c\times (T_{final}-T_{initial})$

$m_1\times c_1\times (T_{final}-T_1)=-[m_2\times c_2\times (T_{final}-T_2)]$ ......(1)

where,

q = heat absorbed or released

$m_1$ = mass of ice = 12.5 g

$m_2$ = mass of water = 85.0 g

$T_{final}$ = final temperature = 22.24°C

$T_1$ = initial temperature of ice = -15.00°C

$T_2$ = initial temperature of water = 25.00°C

$c_1$ = specific heat of ice = ?

$c_2$ = specific heat of water = 4.186 J/g°C

Putting values in equation 1, we get:

$12.5\times c_1\times (22.24-(-15))=-[85.0\times 4.186\times (22.24-25)]$

$c_1=2.11J/g^oC$

Hence, the specific heat of ice is 2.11 J/g°C

3 0

4 years ago

NASA sends an unmanned lander to test conditions on the surface of Mars. What is the magnitude of the gravitational force acting

kozerog [31]

Answer:

The magnitude of the gravitational force acting on the lander on the surface of Mars is 512.46 N.

Explanation:

The Universal law of gravity is define as:

$F = G \frac{M.m}{R^{2}}$ (1)

Where F is the gravitational force, G is gravitational constant, M is the mass of Mars, m is the mass of the lander and R is the radius of Mars.

Before replacing the values in equation 1 it is necessary to express the radius of mars in terms of meters:

R = $3397 kmx\frac{1000 m}{1 km}$ ⇒ R = $3397000 m$

Finally, equation 1 can be used:

$F = (6.67x10^{-11} N.m^{2}/Kg^{2}) \frac{(6.42x10^{23} kg)(138.1 kg)}{(3397000 m)^{2}}$

$F = 512.46 N$

Hence, the magnitude of the gravitational force acting on the lander on the surface of Mars is 512.46 N.

4 0

3 years ago