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3 years ago

Two cars A and B are 100m apart moving towards each other with

Physics

1 answer:

maxonik [38]3 years ago

3 0

Let car A's starting position be the origin, so that its position at time t is

A: x = (40 m/s) t

and car B has position at time t of

B: x = 100 m - (60 m/s) t

They meet when their positions are equal:

(40 m/s) t = 100 m - (60 m/s) t

(100 m/s) t = 100 m

t = (100 m) / (100 m/s) = 1 s

so the cars meet 1 second after they start moving.

They are 100 m apart when the difference in their positions is equal to 100 m:

(40 m/s) t - (100 m - (60 m/s) t) = 100 m

(subtract car B's position from car A's position because we take car A's direction to be positive)

(100 m/s) t = 200 m

t = (200 m) / (100 m/s) = 2 s

so the cars are 100 m apart after 2 seconds.

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The braking distance is the distance traveled by a car experiencing a braking force until it comes to rest.

Our initial energy is solely kinetic:
$E_i = \frac{1}{2}mv^2$

And, since the car goes to rest, it is no longer in motion. It will have no kinetic energy.
$E_f = 0$

Therefore, there was work done by the braking force.

$W_B = E_f - E_i = -\frac{1}{2}mv^2$

Recall the definition of work:
$W = F\cdot \Delta x$

Or in this case, since the displacement and breaking force are antiparallel:
$W = -F_B\Delta x$

This is equivalent to the dissipation of kinetic energy:
$W = -F_B\Delta x = -\frac{1}{2}mv^2$

Now, to visualize this, let's rearrange the equation to solve for displacement.

$\Delta x =\frac{mv^2}{2F_B}$

There is a direct, SQUARE relationship between necessary braking distance speed.

If the speed was reduced by 10.3 percent, its new speed is only 89.7% percent of the original, so:
$\Delta x' =\frac{m(0.897v)^2}{2F_B}$

$\Delta x' = 0.8046\Delta x$

The reduction by a percentage is:
$1 - 0.8046 = 0.1954 \\\\\boxed{= 19.54\%}$

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2 years ago

What is a magnetometer and how does it work?

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Magnetometers are widely used for measuring the Earth's magnetic field and in geophysical surveys to detect magnetic anomalies of various types. They are also used in the military to detect submarines.

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Answer:

6 days.

Explanation:

From radioactivity, The expression for half life is given as,

R/R' = 2⁽ᵃ/ᵇ)................... Equation 1

Where R = original mass of the radioactive substance, R' = Remaining mass of the radioactive substance after decay, a = Total time taken to decay, b = half life.

Given: R = 80 g, R' = 10 g, b = 2 days.

Substitute into equation 1

80/10 = 2⁽ᵃ/²⁾

8 = 2⁽ᵃ/²⁾

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Equating the base and solving for a

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If it takes 600 N to move a box 5 meters, how much work is done on the box?

Anika [276]

Answer:

Option C is the correct option.

Explanation:

Given,

Force = 600 N

Distance = 5 meters

Work = ?

Now,

Work = Force $\times$ distance

$= 600 \times 5$

Calculate the product

$= 3000 \:$ Joule

Hope this helps...

Good luck on your assignment..

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3 years ago

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