Which one will it be

An 1120 kg car traveling at 17 m/s is brought to a stop while skidding 40 m. Calculate the work done on the car by friction forc

sergij07 [2.7K]

Answer:

Approximately $(-1.6 \times 10^{5}\; \rm J)$ (assuming that the car was on level ground.)

Explanation:

When an object of mass $m$ is moving at a speed of $v$ , the kinetic energy of that object would be $(1/2) \, m \cdot v^{2}$ .

Initial kinetic energy of the car:

$\begin{aligned}&\frac{1}{2}\, m \cdot v^{2} \\ &= \frac{1}{2}\times 1120\; \rm kg \times (17\; \rm m \cdot s^{-1})^{2} \\ &\approx 1.6\times 10^{5}\; \rm J \end{aligned}$ .

After the car comes to a stop, the kinetic energy of this car would be $0\; \rm J$ because the car would not be moving.

Change to the kinetic energy of the car: $\text{Final KE} - \text{Initial KE} = -1.6 \times 10^{5}\; \rm J$ .

If the car is traveling on level ground, friction would be the only force that contributed to this energy change. Hence:

$\text{Work of friction} = \text{Energy change} = -1.6\times 10^{5}\; \rm J$ .

The value of the work that friction did is negative. The reason is that at any instant before the car comes to a stop, friction would be exactly opposite to the direction of the movement of the car.

The work of a force on an object is the dot product of that force and the displacement of that object. The dot product of two vectors of opposite directions is negative. Hence, in this question, the work that friction did on the car would be negative because the friction vector would be opposite to the movement of the car.

6 0

3 years ago

6. When sodium and oxygen react to form an ionic compound, the mass of the compound ____ the sum of the masses of the individual

arsen [322]

Because there’s no elemental degradation, the mass of the compound EQUALS the sum of the masses.

3 0

3 years ago

In damped harmonic oscillation, the amplitude of oscillation becomes one third after 2 second. If A0 is initial amplitude of osc

Harman [31]

Answer:

$A=\frac{A_0}{\sqrt 3}$

Explanation:

Initial amplitude= $A_0$

We are given that

Amplitude after 2 s=A= $\frac{1}{3}A_0$

We have to find the amplitude after 1 s.

We know that amplitude at any time t

$A=A_0e^{-\alpha t}$

Using the formula

$\frac{A_0}{3}=A_0e^{-2\alpha}$

$\frac{1}{3}=e^{-2\alpha}$

$3=e^{2\alpha}$

$ln 3=2\alpha$

$\alpha =\frac{ln 3}{2}=ln\sqrt 3$

$e^{\alpha}=\sqrt 3}$

When t=1 s

$A=A_0e^{-\alpha}=\frac{A_0}{\sqrt 3}$

8 0

4 years ago

What is a goal of the planned missions MIRI? <br>the answer is to explore the kupier belt

VMariaS [17]

Answer:

Its goal is to explore the Kupier Belt, a region in space where comets originate

Explanation:

The Mid-Infrared Instrument (MIRI) is a telescope with abilities to see the mid-infrared region of the electromagnetic spectrum.The wavelength of this instrument is 5-28 microns. The Kupier belt is a region in space beyond Neptune.MIRI was developed to enable scientists study and explore the kupier belt to observe the far most galaxies, new stars that are formed and the comets invisible from the previous telescopes.

8 0

3 years ago

Why is the mechanical advantage of using a single pulley always 1? Assume there’s no friction. A. The input force is in a differ

STALIN [3.7K]

The answer is D. The input force is equal to the output force.

I just did test and got it right

3 0

4 years ago

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