Physics, 01.01.2021 16:00 warrenclanrocks

An object of mass 6 kg. is resting on a horizontal surface. A horizontal force of 15 N is constantly applied on the object. The object moves a distance of
100m in 10 seconds.
(a) How much work does the applied force do?
(b) What is the kinetic energy of the block after 10 seconds?
(c) What is the magnitude and direction of the frictional force (if there is
any)?
(d) How much energy is lost during motion?

Answers: 2

Show answers

Answers

Answer from: 5theth

a) The work done by the applied force is 1500 joules.

b) The kinetic energy of the block after 10 seconds is 1200 joules.

c) The magnitude of the force of friction is 3 newtons and its direction is against motion.

d) 300 joules of energy are lost during motion.

Explanation:

a) Since the object has a constant mass, on which a constant horizontal force is exerted. The work done by the force (), measured in joules, is defined by the following expression:

$W = F\cdot \Delta x$ (1)

Where:

- Force, measured in newtons.

$\Delta x$ - Distance, measured in meters.

If we know that $F = 15\,N$ and $\Delta x = 100\,m$ , then the work done by the force exerted on the object is:

$W = (15\,N)\cdot (100\,m)$

$W = 1500\,J$

The work done by the applied force is 1500 joules.

b) At first we need to calculate the net acceleration of the object (), measured in meters per square second. By assuming a constant acceleration, we use the following kinematic formula:

$\Delta x = v_{o}\cdot t +\frac{1}{2}\cdot a\cdot t^{2}$ (2)

Where $v_{o}$ is the initial velocity of the object, measured in meters per second.

We clear the acceleration within the equation above:

$\frac{1}{2}\cdot a \cdot t^{2} = \Delta x-v_{o}\cdot t$

$a = \frac{2\cdot (\Delta x - v_{o}\cdot t)}{t^{2}}$

If we know that $\Delta x = 100\,m$ , $v_{o} = 0\,\frac{m}{s}$ and $t = 10\,s$ , then the net acceleration experimented by the object is:

$a = \frac{2\cdot \left[100\,m-\left(0\,\frac{m}{s} \right)\cdot (10\,s)\right]}{(10\,s)^{2}}$

$a = 2\,\frac{m}{s^{2}}$

By the 2nd Newton's Law, we construct the following equation of equilibrium under the consideration of a friction force acting against the motion of the object:

$\Sigma F = F - f = m\cdot a$ (3)

Where:

- External force exerted on the object, measured in newtons.

- Kinetic friction force, measured in newtons.

If we know that $F = 15\,N$ , $m = 6\,kg$ and $a = 2\,\frac{m}{s^{2}}$ , the kinetic friction force is:

$f = F-m\cdot a$

$f = 15\,N-(6\,kg)\cdot \left(2\,\frac{m}{s^{2}} \right)$

$f = 3\,N$

The work done by friction (), measured in joules, is:

$W' = f\cdot \Delta x$ (4)

$W' = (3\,N) \cdot (100\,m)$

$W' = 300\,J$

And the net work experimented by the object is:

$\Delta W = 1500\,J - 300\,J$

$\Delta W = 1200\,J$

By the Work-Energy Theorem we understand that change in translational kinetic energy ( $\Delta K$ ), measured in joules, is equal to the change in net work. That is:

$\Delta K = \Delta W$ (5)

If we know that $\Delta W = 1200\,J$ , then the change in translational kinetic energy is:

$\Delta K = 1200\,J$

The kinetic energy of the block after 10 seconds is 1200 joules.

c) The magnitude of the force of friction is 3 newtons and its direction is against motion.

d) The energy lost by the object is equal to the work done by the force of friction. Therefore, 300 joules of energy are lost during motion.

Answer from: Quest

answer: you might love summer weather, but you don’t want it to feel like the sun is inside your car. but a hot car that just won’t seem to cool down might be a bigger of a problem than you think. your car relies on being at the right temperature.

explanation:

Answer from: Quest

the duration of a photographic flash is related to an rc time constant, which is 0.100 μs for a certain camera.

Another question on Physics

Physics, 21.06.2019 14:30

Aray diagram for a refracted light day is shown. what does the dashed line represent

Answers: 2

Answer

Physics, 22.06.2019 11:30

The least penetrating form of radiation is

Answers: 1

Answer

Physics, 22.06.2019 17:40

A15.75-g piece of iron absorbs 1086.75 joules of heat energy, and its temperature changes from 25°c to 175°c. what is the specific heat capacity of iron?

Answers: 1

Answer

Physics, 22.06.2019 19:30

How many electrons in an atom could have these sets of quantum numbers? =3n=3 electronselectrons =4,ℓ=2n=4,ℓ=2 electronselectrons =6,ℓ=ℓ=−1n=6,ℓ=2,mℓ=−1

Answers: 3

Answer

You know the right answer?

An object of mass 6 kg. is resting on a horizontal surface. A horizontal force of 15 N is constantl...

Questions