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Rainbow [258]
3 years ago
15

A block starting from rest slides down the length of an 18 plank with an acceleration of 4.0 meters per second. How long does th

e block take to reach the bottom?
Physics
1 answer:
Snowcat [4.5K]3 years ago
4 0

Answer:

\boxed{\text{\sf \Large 3.0 s}}

Explanation:

Use distance formula

\displaystyle d=ut+\frac{1}{2} at^2

u= \text{\sf  initial velocity}\\d= \text{\sf  distance}\\a= \text{\sf  acceleration}\\t= \text{\sf  time taken}

\displaystyle 18=0 \times t+\frac{1}{2} \times 4 \times t^2

t=3

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According to a rule-of-thumb. every five seconds between a lightning flash and the following thunder gives the distance to the f
Bond [772]

Answer:

S_{s}=300 m/s

The rule for kilometers is that every three seconds between a lightning flash and the following thunder gives the distance to the flash in kilometers.

Explanation:

In order to use the rule of thumb to find the speed of sound in meters per second, we need to use some conversion ratios. We know there is 1 mile per every 5 seconds after the lightning is seen. We also know that there are 5280ft in 1 mile and we also know that there are 0.3048m in 1ft. This is enough information to solve this problem. We set our conversion ratios like this:

\frac{1mi}{5s}*\frac{5280ft}{1mi}*\frac{0.3048m}{1ft}=321.87m/s

notice how the ratios were written in such a way that the units got cancelled when calculating them. Notice that in one ratio the miles were on the numerator of the fraction while on the other they were on the denominator, which allows us to cancel them. The same happened with the feet.

The problem asks us to express the answer to one significant figure so the speed of sound rounds to 300m/s.

For the second part of the problem we need to use conversions again. This time we will write our ratios backwards and take into account that there are 1000m to 1 km, so we get:

\frac{5s}{1mi}*\frac{1mi}{5280ft}*\frac{1ft}{0.3048m}*\frac{1000m}{1km}=3.11s/km

This means that for every 3.11s there will be a distance of 1km from the place where the lightning stroke. Since this is a rule of thumb, we round to the nearest integer for the calculations to be made easily, so the rule goes like this:

The rule for kilometers is that every three seconds between a lightning flash and the following thunder gives the distance to the flash in kilometers.

3 0
3 years ago
17.a car is traveling at a constant velocity of 60 km/h for 4 hours means
Setler [38]
<span>Assuming the car is travelling in the same direction for the entire hour, the acceleration is zero.</span>
7 0
3 years ago
The combustion of ethanol, C2H5OH(l), in oxygen to form carbon dioxide gas and water vapor is shown by which balanced chemical e
NemiM [27]
C2H5OH (l) + 3 O2 (g) = 2 CO2 (g)+ 3 H2O (l/g)
4 0
3 years ago
g A bowling ball with a mass of 3.86 kg and a radius of 0.161 m starts from rest at a height of 2.5 m and rolls down a 48.4 o sl
Fynjy0 [20]

Answer:

v=1.5m/s

Explanation:

The gravitational potential energy gets transformed into translational and rotational kinetic energy, so we can write mgh=\frac{mv^2}{2}+\frac{I\omega^2}{2}. Since v=r\omega (the ball rolls without slipping) and for a solid sphere I=\frac{2mr^2}{5}, we have:

mgh=\frac{mv^2}{2}+\frac{2mr^2\omega^2}{2*5}=\frac{mv^2}{2}+\frac{mv^2}{5}=\frac{7mv^2}{10}

So our translational speed will be:

v=\sqrt{\frac{10gh}{7}}=\sqrt{\frac{10(9.8m/s^2)(0.161m)}{7}}=1.5m/s

6 0
2 years ago
Definition of continental polar
kipiarov [429]

Answer:

Continental polar (cP) or continental arctic (cA) air masses are cold, dry, and stable. These air masses originate over northern Canada and Alaska as a result of radiational cooling. Maritime polar (mP) air masses are cool, moist, and unstable.

Explanation:

8 0
2 years ago
Read 2 more answers
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