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3 years ago

a car accelerates uniformly from rest to a speed of 65 km/h (18 m/s) in 12s. Find the distance the car travels during this time?

1 answer:

5 0

The car's speed was zero at the beginning of the 12 seconds,
and 18 m/s at the end of it. Since the acceleration was 'uniform'
during that time, the car's average speed was (1/2)(0 + 18) = 9 m/s.

12 seconds at an average speed of 9 m/s ==> (12 x 9) = 108 meters .

==========================================

That's the way I like to brain it out. If you prefer to use the formula,
the first problem you run into is: You need to remember the formula !

The formula is D = 1/2 a T²

   Distance = (1/2 acceleration) x (time in seconds)²

   Acceleration = (change in speed) / (time for the change)
    = (18 m/s) / (12 sec)
    = 1.5 m/s² .

Distance = (1/2 x 1.5 m/s²) x (12 sec)²
      =     (0.75 m/s²) x (144 sec²) = 108 meters .

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Answer:

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3 years ago

A box is pulled to the right with a force of 65 N at an angle of 58 degrees to the horizontal. The surface is frictionless. The

Citrus2011 [14]

The free-body diagram is missing, but I assume the only forces acting on the box are the force F pushing the box, the weight of the object and the normal reaction of the surface.

Since the weight and the normal reaction acts in the vertical (y) direction, the only force acting on the box in the horizontal (x) direction is the horizontal component of the force F, which is given by
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3 years ago

Read 2 more answers

A 1.0 × 10^3 kg sports car is initially traveling at 15 m/s. The driver then applies the brakes for several seconds so that -25

algol13

Answer:

Ea = 112500[J]

Eb = 87500[J]

Explanation:

To solve this problem we must use the principle of energy conservation which tells us that the energy of a body plus the work done or applied by the body equals the final energy of a body.

This can be easily visualized by the following equation:

$E_{A}+E_{friction}=E_{B}$

Now we must define the energies at points A & B.

<u>For point A</u>

At point A we only have kinetic energy since it moves at 15 [m/s]

So the kinetic energy

$E_{A}=\frac{1}{2}*m*v_{A}^{2} \\E_{A}=\frac{1}{2} *1000*(15)^{2} \\E_{A}=112500[J]$

The final kinetic energy can be calculated as follows:

$112500-25000=E_{B}\\E_{B}=87500[J]$

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3 years ago

A bicycle odometer which counts revolutions and is calibrated to report distance traveled is attached near the wheel axle and is

Bess [88]

Answer:

each rotation of the smaller wheel will show 84.382-75.3982=8.9838 inches more than the actual distance

Explanation:

d = Diameter of the wheel

The distance traveled in one rotation of the wheel is the circumference of the wheel

$\pi d=\pi\times 27\\ =84.823\ inch$

When diameter is 24 inches

$\pi d=\pi\times 24\\ =75.3982\ inch$

Therefore, each rotation of the smaller wheel will show 84.382-75.3982=8.9838 inches more than the actual distance

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3 years ago

holiday lights are often connected in series and use special lamps that short out when the potential difference across a lamp in

Nuetrik [128]

Explanation:

If there isn't the shorting mechanism, the whole set will be blown if anyhow one lamp burns out. Since having blown out several lamps and then shorted, the overall resistance of the remaining operating lamps will be decreased resulting in an increased working current that is adequate to blast the fuse.

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4 years ago