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3 years ago

15

Help me plz.Show workings

2 answers:

Ksenya-84 [330]3 years ago

8 0

This question is a good example of the difference between 'speed' and 'velocity'. This one is all 'velocity', and you've absolutely gotta keep the directions straight.

The object started out moving forward at 10 m/s. It ended up moving backward at 2 m/s. What was the change in its velocity ?

The change was <u>12 m/s backward</u> !

Momentum = (mass) x (velocity).

Change in momentum = (mass) x (change in velocity)

This change in momentum = (0.1 kg) x (12 m/s backward)

This change in momentum = 1.2 m/s backward or <em>1.2 Ns (B)</em>

ddd [48]3 years ago

3 0

Change in momentum: finial momentum - initial momentum
Momentum = mass * velocity
Mass = 100g, same as 0.1kg
m(v-u) = 0.1(10-2) = 0.1(8)
The answer is 0.8Ns

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the kinetic energy of an object with mass m moving with a velocity of 5 m/s is 25 j what will be its kinetic energy when its vel

Dmitriy789 [7]

Answer:

100 J, 225 J

Explanation:

The kinetic energy of an object is given by:

$K=\frac{1}{2}mv^2$

where

m is the mass of the object

v is the velocity of the object

In this problem, the initial kinetic energy of the object is

K = 25 J

Then, the velocity is doubled, which means

v' = 2v

Therefore, the new kinetic energy will be

$K'=\frac{1}{2}m(2v)^2 = 4(\frac{1}{2}mv^2)=4K$

Therefore, the kinetic energy has quadrupled:

$K' = 4(25)=100 J$

Later, the velocity is tripled, which means

v'' = 3v

Therefore, the new kinetic energy will be

$K''=\frac{1}{2}m(3v)^2 = 9(\frac{1}{2}mv^2)=9K$

Therefore, the kinetic energy has increased by a factor of 9:

$K' = 9(25)=225 J$

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3 years ago

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2 years ago

A box of mass m is pushed at an angle 0 by a force Fp along a frictionless surface. The box travels to right with acceleration a

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2 years ago

Read 2 more answers

An explorer is caught in a whiteout (in which the snowfall is so thick that the ground cannot be distinguished from the sky) whi

Veronika [31]

Answer:

$s=5.79\ km$

$\theta=47^{\circ}$ east of south

Explanation:

Given:

distance of the person form the initial position, $d'=8.4\ km$

direction of the person from the initial position, $47^{\circ}$ north of east

distance supposed to travel form the initial position, $d=5.3\ km$

direction supposed to travel from the initial position, due North

<u>Now refer the schematic for visualization of situation:</u>

$y=d'.\sin47^{\circ}-d$

$y=8.4\times \sin47-5.3$ ...............(1)

$x=d'.\cos47^{\circ}$

$x=8.4\times \cos47^{\circ}$ .................(2)

<u>Now the direction of the desired position with respect to south:</u>

$\tan\theta=\frac{y}{x}$

$\tan\theta=\frac{8.4\times \sin47}{8.4\times \cos47}$

$\theta=47^{\circ}$ east of south

<u>Now the distance from the current position to the desired position:</u>

$s=\sqrt{x^2+y^2}$

$s=\sqrt{(8.4\times \cos47)^2+(8.4\times \sin47-5.3)^2}$

$s=5.79\ km$

4 0

3 years ago

An object has traveled 20 meters in 40 seconds what is its average speed

Mice21 [21]

Hello,

To solve we need to know the formula for speed

The formula is D/T=S (Distance of time=speed)

Now all we have to do is plug in the numbers.

20/40= 1/2 or 0.5

SO the speed is 0.5 m/s

Have a great day!

6 0

3 years ago