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3 years ago

A man in a lift is moving upwards in a constant speed.the weight of the man is W.Acc

Physics

1 answer:

Nookie1986 [14]3 years ago

3 0

Answer:

Normal force=mg

Explanation:

The reaction force of weight is the normal force.

in order to find the normal for we need to write all the forces and set it equal to the net force:

N-mg=ma (since it is a constant speed the a=0)

N=mg

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PLEASE HELP! URGENT Explain how the forces need to change so an aeroplane can land

dangina [55]

Answer:

it changes by taking the air from below the plane and curving it to the top causing draw wich slows it down then the weight that pulls it down to land.

please put me brainliest

Explanation:

6 0

3 years ago

A river 500 ft wide flows with a speed of 8 ft/s with respect to the earth. A woman swims with a speed of 4 ft/s with respect to

White raven [17]

Answer:

1) $\Delta s=1000\ ft$

2) $\Delta s'=998.11\ ft.s^{-1}$

3) $t\approx125\ s$

$t'\approx463.733\ s$

Explanation:

Given:

width of river, $w=500\ ft$

speed of stream with respect to the ground, $v_s=8\ ft.s^{-1}$

speed of the swimmer with respect to water, $v=4\ ft.s^{-1}$

Now the resultant of the two velocities perpendicular to each other:

$v_r=\sqrt{v^2+v_s^2}$

$v_r=\sqrt{4^2+8^2}$

$v_r=8.9442\ ft.s^{-1}$

Now the angle of the resultant velocity form the vertical:

$\tan\beta=\frac{v_s}{v}$

$\tan\beta=\frac{8}{4}$

$\beta=63.43^{\circ}$

Now the distance swam by the swimmer in this direction be d.

so,

$d.\cos\beta=w$

$d\times \cos\ 63.43=500$

$d=1118.034\ ft$

Now the distance swept downward:

$\Delta s=\sqrt{d^2-w^2}$

$\Delta s=\sqrt{1118.034^2-500^2}$

$\Delta s=1000\ ft$

On swimming 37° upstream:

The velocity component of stream cancelled by the swimmer:

$v'=v.\cos37$

$v'=4\times \cos37$

$v'=3.1945\ ft.s^{-1}$

Now the net effective speed of stream sweeping the swimmer:

$v_n=v_s-v'$

$v_n=8-3.1945$

$v_n=4.8055\ ft.s^{-1}$

The component of swimmer's velocity heading directly towards the opposite bank:

$v'_r=v.\sin37$

$v'_r=4\sin37$

$v'_r=2.4073\ ft.s^{-1}$

Now the angle of the resultant velocity of the swimmer from the normal to the stream:

$\tan\phi=\frac{v_n}{v'_r}$

$\tan\phi=\frac{4.8055}{2.4073}$

$\phi=63.39^{\circ}$

Now let the distance swam in this direction be d'.

$d'\times \cos\phi=w$

$d'=\frac{500}{\cos63.39}$

$d'=1116.344\ ft$

Now the distance swept downstream:

$\Delta s'=\sqrt{d'^2-w^2}$

$\Delta s'=\sqrt{1116.344^2-500^2}$

$\Delta s'=998.11\ ft.s^{-1}$

Time taken in crossing the rive in case 1:

$t=\frac{d}{v_r}$

$t=\frac{1118.034}{8.9442}$

$t\approx125\ s$

Time taken in crossing the rive in case 2:

$t'=\frac{d'}{v'_r}$

$t'=\frac{1116.344}{2.4073}$

$t'\approx463.733\ s$

7 0

4 years ago

An ambulance is currently traveling at 25 m/s, and is accelerating with a constant acceleration of 5 m/s^2. The ambulance is att

bazaltina [42]

Answer:

PLEASE MARK ME BRAINLIEST!!!

Explanation:

Given initial velocity of ambulance

v0=18m/s , acceleration a=5m/s2

To find distance, x=?

First we need to calculate the time for which it acquires 30\,m/s. For that use equation

v=v0+at

30=18+5×t

⇒t=30−185=125seconds

Distance travelled by the ambulance

x=v0t+12at2

x=(18×125)+12×5×(125)2

x=43.2+2.5×5.76=43.2+14.4

x=57.6m

Therefore the ambulance has to travel 57.6 m to match the velocity of car.

5 0

2 years ago

The following table shows the duration of a year on some unknown planets of equal mass. Duration of Year Planet Duration of Year

Soloha48 [4]

Gravitational force between sun and planet is given by,

$F=\frac{GMm}{r^{2}}$

Thus, The force of gravitation is inversely proportional to the distance.

Kepler's law states that the square of period of planet is proportional to cube of semi major axis of its orbit.

The time period of planet is more when the gravitational force is less.

Thus, planet Y is closer to earth because sun exert greater gravitational force than planet Z.

8 0

4 years ago

Read 2 more answers

A rolling ball has 8 joules of kinetic energy and is rolling 4m/s. Find it’s mass

Maru [420]

Answer:

m = 1

Explanation:

K.E = 8J

v = 4m/s

m = ?

Now,

K.E = 1÷2mv^2

8 = 1÷2 × m × (4)^2

8 = 1÷2 × m × 16

8 = m × 8

m × 8 = 8

m = 8 ÷ 8 = 1

m = 1

<h3>VERIFICATION:</h3>

K.E. = 1÷2mv^2

K.E = 1÷2 × 1 × 4^2

K.E. = 8J

-TheUnknownScientist

4 0

3 years ago