All categories

3 years ago

Could anyone help me figure out d and e? How can you find the work of the friction when the force of friction is not given?

Physics

1 answer:

IRINA_888 [86]3 years ago

3 0

Wow ! This is not simple, Shoot, and I give you a lot of credit
and an extra merit badge if you're generally keeping up with it.

I scratched my head for a few minutes, and I think I've got it.
Here's what I think is going on:

KE₁ = KE of the box before pushing
   (1/2) (m) (speed²) = 10 x 2² = 40 joules

KE₂ = KE of the box after pushing 3m
   (1/2) (m) (speed²) = 10 x 4² = 160 joules

The box gained (160 - 40) = 120 J of kinetic energy.

Now look at the cluttered force diagram.
Cat's component of force in the direction of motion is 120N.
That's the part of her force that does the work on the box.
How much work does she do ?

   (force) x (distance) = (120N) x (3m) = 360 joules .

Only 120 J of that energy showed up as increased kinetic energy
of the box. The other 240J of her hard-earned work was consumed
by friction.

   Work of friction = (Friction force) x (distance)

   240 J = (friction force) x (3 m)

240 J / 3 m = friction 'force' = 80 N .

I think that's it.

What I did was:

-- Find the work that Cat did.

-- Find the increase in the kinetic energy of the box.

-- The difference ... the 'missing energy' ... was the work done
by friction in the same distance.

Does this do anything for you ?

You might be interested in

A 12-volt automotive circuit has a current of 3 amps. Technician A says the electric power in this circuit is 36 watts. Technici

skelet666 [1.2K]

Answer:

Technician A is right.

Explanation:

Given that,

Voltage of circuit, V = 12 volt

Current in the circuit, I = 3 A

Technician A says the electric power in this circuit is 36 watts. Technician B says the electric power in this circuit is 4 watts. We need to say that which technician is correct.

The power of any circuit is given by :

$P=V\times I$

$P=12\ V\times 3\ A$

P = 36 watts

So, technician A is right. Hence, this is the required solution.

6 0

2 years ago

25. Explain why the speed of sound is faster in solids than in gases. Include two other factors Chapter 17 says the speed of sou

aksik [14]

In solids, particles or atom are very closely arranged compared to gasses. When these particles are arranged in such proximity, vibrations from sound are very easily transmitted from one particle to another in the solid. Hence, the sound vibrations can travel through the solid medium more quickly than through a gas medium.
Speed of sound also depends on its frequency and the wavelength.

7 0

2 years ago

When landing after a spectacular somersault, a 35.0 kg gymnast decelerates by pushing straight down on the mat. calculate the fo

Sliva [168]

The deceleration experienced by the gymnast is the 9 times of the acceleration due to gravity.

Now from Newton`s first law, the net force on gymnast,

$F_{net} =F-W=ma$

Here, W is the weight of the gymnast and a is the acceleration experienced by the gymnast ( $9\times g$ acceleration due to gravity)

Therefore,

$F= ma+W$ OR $F=ma+mg=m(g+a)$

Given $m = 30 kg$ and $a=9\times g=9\times 9.8 m/s^{2} =88.2 m/s^{2}$

Substituting these values in above formula and calculate the force exerted by the gymnast,

$F=(40 kg) (88.2 m/s^{2} +9.8 m/s^{2} )$

$F=3.537\times10^{3}N$

6 0

3 years ago

A uniform disk with a mass of 5.0 kg and diameter 30 cm rotates on a frictionless fixed axis through its center and perpendicula

igomit [66]

Answer:

Angular acceleration of the disk will be $\alpha =10.714rad/sec^2$

Explanation:

We have given mass of the disk m = 5 kg

Diameter of the disk d = 30 cm = 0.3 m

So radius $r=\frac{d}{2}=\frac{0.3}{2}=0.15m$

Moment of inertia of disk is given by $I=\frac{1}{2}mr^2=\frac{1}{2}\times 5\times 0.15^2=0.056kgm^2$

Force is given by F=4 N

Torque is given as $\tau =Fr=4\times 0.15=0.6N-m$

We also know that torque is given by $\tau =I\alpha$

$0.6=0.056\times \alpha$

$\alpha =10.714rad/sec^2$

5 0

3 years ago

What is the difference between radial acceleration and tangential acceleration and how do you calculate both of these accelerati

sergey [27]

Answer:

Tangential acceleration is in the direction of velocity - along the circumference of a circle if the object is undergoing circular motion

a = (V2 - V1) / T

Radial acceleration is perpendicular to the direction of motion if the object is not moving in a straight line (perhaps along the circumference of a circle)

a = m V^2 / R = m ω^2 R where R is the radius vector of the velocity - note that the Radius vector is directed from the center of motion to the object and for circular motion would be constant in magnitude but not in direction

8 0

1 year ago