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3 years ago

A 10 Kg dog is running with a speed of 5.0 m/s what is the minimum work required to stop the dog

Physics

1 answer:

ra1l [238]3 years ago

8 0

Answer:

25J

Explanation:

Given parameters:

Mass of the dog = 10kg

Speed of the dog = 5m/s

Unknown:

The minimum energy required to stop the dog = ?

Solution:

The dog is moving with a kinetic energy and to stop the dog, an equal amount of kinetic energy generated must be applied to the dog.

To find the kinetic energy;

K.E = $\frac{1}{2}$ m v²

m is the mass

v is the velocity

Now insert the parameters and solve;

K.E = $\frac{1}{2}$ x 10 x 5 = 25J

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Leviafan [203]

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2 years ago

Two small objects each with a net charge of +Q exert a force of magnitude F on each other. We replace one of the objects with an

Alona [7]

Answer:

F'= 4F/9

Explanation:

Two small objects each with a net charge of +Q exert a force of magnitude F on each other. If r is the distance between them, then the force is given by :

$F=\dfrac{kQ^2}{r^2}$ ...(1)

Now, if one of the objects with another whose net charge is + 4Q is replaced and also the distance between +Q and +4Q charges is increased 3 times as far apart as they were. New force is given by :

$F'=\dfrac{kQ\times 4Q}{(3r)^2}\\\\F'=\dfrac{4kQ^2}{9r^2}$ .....(2)

Dividing equation (1) and (2), we get :

$\dfrac{F}{F'}=\dfrac{\dfrac{kQ^2}{r^2}}{\dfrac{4kQ^2}{9r^2}}\\\\\dfrac{F}{F'}=\dfrac{kQ^2}{r^2}\times \dfrac{9r^2}{4kQ^2}\\\\\dfrac{F}{F'}=\dfrac{9}{4}\\\\F'=\dfrac{4F}{9}$

Hence, the correct option is (d) i.e. " 4F/9"

7 0

2 years ago

A bungee cord can stretch, but it is never compressed. When the distance between the two ends of the cord is less than its unstr

Ksju [112]

Answer:

Explanation:

Given that

g=9.8m/s²

The spring constant is

k=50N/m

The length of the bungee cord is

Lo=32m

Height of bridge which one end of the bungee is tied is 91m

A steel ball of mass 92kg is attached to the other end of the bungee.

The potential energy(Us) of the steel ball before dropped from the bridge is given as

P.E= mgh

P.E= 92×9.8×91

P.E= 82045.6 J

Us= 82045.6 J

Potential energy)(Uc) of the cord is given as

Uc= ½ke²

Where 'e' is the extension

Then the extension is final height extended by cord minus height of cord

e=hf - hi

e=hf - 32

Uc= ½×50×(hf-32)²

Uc=25(hf-32)²

Using conservation of energy,

Then,

The potential energy of free fall equals the potential energy in string

Uc=Us

25(hf-32)²=82045.6

(hf-32)² = 82045.6/25

(hf-32)²=3281.825

Take square root of both sides

√(hf-32)²=√(3281.825)

hf-32=57.29

hf=57.29+32

hf=89.29m

We neglect the negative sign of the root because the string cannot compressed

3 0

3 years ago

A car drives to the east in a time of 4 hours. Then, immediately (not realistic, but just assume this is the case for this probl

diamong [38]

Answer:

Average speed in east direction $speed=\frac{distance}{time}=\frac{28}{4}=7km/hr$

Explanation:

We have given average speed of the entire trip = 5 km/hr

First the car 4 hours then travels 12 km in 4 hours

So total time of the trip = 4+4 = 8 hours

So total distance traveled in the trip $d=speed\times time = 5\times 8=40km$

As the car travel 12 km in 4 hours to the west

So distance traveled in 4 hour in east = 40 -12 = 28 km

Time in east direction = 4 hour

So average speed in east direction $speed=\frac{distance}{time}=\frac{28}{4}=7km/hr$

4 0

2 years ago

URGENT!!!!! If a 6 Ω resistor is in a circuit connected to a voltage source, and the current through the circuit is 2 amps, what

Eduardwww [97]

Answer:

Explanation:

according to ohms law we know that

v=IR

given current =2 amps

given resistance =6Ω

so voltage is

v=2*6 =12 V

3 0

3 years ago