Ask question

Ask question

All categories

Veseljchak [2.6K]

2 years ago

15

An airplane starts from A and flies to B at a constant speed. After reaching B it returns to A at the same speed. There was no w

ind. Assuming there was a wind from A to B of constant magnitude, when will the round trip take more time – when there is a wind or when there is no wind?

1 answer:

Dafna1 [17]2 years ago

4 0

Answer:

When there is wind it takes longer

Explanation:

With no wind, the round trip time is

$t_1=\frac{d}{v}+\frac{d}{v}=\frac{2d}{v}$

When we have a constant wind speed w

$t_2=\frac{d}{v-w} +\frac{d}{v+w} =\frac{2vd}{v^{2} -w^{2}}$

comparing the reciprocal times;

$\frac{1}{t_2}=\frac{v^{2}-w^{2} }{2vd}=\frac{v}{2d}-\frac{w^{2}}{2vd} \leq \frac{v}{2d}=\frac{1}{t_1}$

This means that t1 is smaller than t2, ergo, it takes longer with wind

You might be interested in

A car accelerates from rest at 2 m/s. what is the speed after 8 sec?

beks73 [17]

Answer:

16m/s

Explanation:

$v_{f}=v_{i}+at$

$v_{f}=0+2\cdot8$

$v_{f}=16\ \frac{m}{s}$

Therefore, the speed after 8 seconds is 16m/s

6 0

1 year ago

Please help me do this problem

Digiron [165]

Answer:

i) acceleration from B to D is 0, because the velocity is constant (stays the same)

ii) whatever units of distathat might be, we can calculate the number:

for 4 time-steps (2 to 6) the velocity is 6 per time step, that makes 24 distance units in these 4 time steps. it's the same the area underneath the graph.

there is also the vertical line from 0 to 2. we can calculate that distance like the area of a triangle with 2*6 / 2 = 6

the total distance from 0 to D is therefore 30

4 0

2 years ago

A bowler throws a bowling ball of radius R = 11 cm down the lane with initial speed v₀ = 7.5 m/s. The ball is thrown in such a w

salantis [7]

Answer:

a) t = 0.74s

b) D = 4.76m

c) Vf = 5.35m/s

Explanation:

The ball starts rolling when Vf = ωf*R.

We know that:

Vf = Vo - a*t

ωf = ωo + α*t

With a sum of forces on the ball:

$Ff = m*a$

$\mu*N = m*a$

$\mu*m*g = m*a$

$a=\mu*g=2.9m/s^2$

With a sum of torque on the ball:

$Ff*R = I*\alpha$

$\mu*m*g*R = 2/5*m*R^2*\alpha$

$\alpha=5/2*\mu*g/R=65.9rad/s^2$

Replacing both accelerations:

$Vo - a*t=\alpha*t*R$

$7.5 - 2.9*t=65.9*t*0.11$

t=0.74s

The distance will be:

$D = Vo*t-1/2*a*t^2$

$D = 4.76m$

Final velocity:

$Vf=Vo-a*t$

Vf=5.35m/s

7 0

2 years ago

An proton-antiproton pair is produced by a 2.20 × 10 3 MeV photon. What is the kinetic energy of the antiproton if the kinetic e

timama [110]

Answer:

K = 80.75 MeV

Explanation:

To calculate the kinetic energy of the antiproton we need to use conservation of energy:

$E_{ph} = E_{p} + E_{ap} = E_{0p} + K_{p} + E_{0ap} + K_{ap} = m_{0p}c^{2} + K_{p} + m_{0ap}c^{2} + K_{ap}$

<em>where $E_{ph}$ : is the photon energy, $E_{0p} and E_{0ap}$ : are the rest energies of the proton and the antiproton, respectively, equals to m₀c², $K_{p} and K_{ap}$ : are the kinetic energies of the proton and the antiproton, respectively, c: speed of light, and m₀: rest mass.</em>

Therefore the kinetic energy of the antiproton is:

$K_{ap} = E_{ph} - m_{0p}c^{2} - K_{p} - m_{0ap}c^{2}$

<u>The proton mass is equal to the antiproton mass, so</u>:

$K_{ap} = E_{ph} - 2m_{0p}c^{2} - K_{p}$

$K_{ap} = 2.20 \cdot 10^{3}MeV - 2(1.67 \cdot 10^{-27}kg)(3\cdot 10^{8} \frac {m}{s})^{2} - 242.85MeV$

$K_{ap} = 2.20 \cdot 10^{3}MeV - 2(1.67 \cdot 10^{-27}kg)(3\cdot 10^{8} \frac {m}{s})^{2}(\frac{1eV}{1.602 \cdot 10^{-19}J})(\frac{1 MeV}{10^{6}eV}) - 242.85MeV$

$K_{ap} = 80.75 MeV$

Hence, the kinetic energy of the antiproton is 80.75 MeV.

I hope it helps you!

3 0

2 years ago

Which data set has the largest range?

MrRissso [65]

Answer:

Option C

Explanation:

We have to check range of all options first

For A:

Largest Value: 5

Smallest Value: 1

So range = Largest value - smallest value

5-1 = 4

For B:

Largest Value: 6

Smallest Value: 4

Range = 6-4 = 2

For C:

Largest Value: 9

Smallest Value: 1

Range = 9-1 = 8

For D:

Largest Value = 9

Smallest Value = 3

Range = 9-3=6

So, the data set in option C has the largest range

4 0

2 years ago