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Lyrx [107]
3 years ago
10

A general contractor drives 5 miles to the hardware store in 10 minutes. He shops for needed tools for 30 minutes, then drives t

o his customer’s home at an average speed of 45 mph. He arrives 20 minutes later. Calculate the average speed from the time the contractor leaves his office to the time he arrives at his customer’s home.
Physics
1 answer:
Alex17521 [72]3 years ago
3 0

Given parameters:

Distance to hardware shop = 5 miles

Time to reach hardware shop = 10 minutes

Time spent at the shop = 30 minutes

Average speed to customer home = 45 mph

Time taken for the travel = 20 minutes

Unknown:

Average speed of the contractor = ?

Solution:

 Average speed is the total distance covered divided by the total time taken.

   Average speed = \frac{total distance}{total time taken}  

     total distance = distance to hardware shop + distance to customer's home

We do not know the distance to customer's home but we have been given the speed and time, so we can find the distance.

  Distance  = speed x time

 Convert the time to hrs and solve;  

                       60 minutes  = 1 hr

                       20 minutes  = \frac{20}{60} hr  = \frac{1}{3} hr

So, Distance  = 45mph x \frac{1}{3} hr   = 15miles

Now;

   Total distance  = 5 + 15 = 20miles

Total time = time to reach hardware shop + time to reach customer's house

                  = 10 + 20

                  = 30 minutes

Convert the time from minutes to hrs;

                 60 minutes  = 1hr

                 30 minutes  = \frac{30}{60}   = 0.5hr

So;

    Average speed  = \frac{20}{0.5} = 40mph

The average speed is 40mph

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The answer to the question

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. Two identical vehicles traveling at the same speed are made to collide with barriers in an insurance company collision test. T
Serggg [28]

Answer:

F₁ / F₂ = 10

therefore the first out is 10 times greater than the second barrier

Explanation:

For this exercise let's use the relationship between momentum and momentum.

         I = F t = Δp

in this case the final velocity is zero

        F t = 0 -m v₀

        F = m v₀ / t

in order to answer the question we must assume that the two vehicles have the same mass and speed

concrete barrier

        F₁ = -p₀ / 0.1

        F₁ = - 10 p₀

barrier collapses

         F₂ = -p₀ / 1

let's look for the relationship of the forces

        F₁ / F₂ = 10

therefore the first out is 10 times greater than the second barrier

5 0
2 years ago
Explain in terms of impulse how padding reduces forces in a collision. State this in terms of a real example, such as the advant
Lena [83]

Answer:

Impulse = Average force x time of contact

Explanation:

Impulsive force is a force which is very large but applied on a body for a very small duration of time.

Impulse is given by the change in momentum of the body.

Impulse = Average force x small time interval

When padding is there, the time interval of contact is large and thus, the force exerted by the body is small.

So, when a person falls on the tile floor, there is no compression and thus, the time of contact is very small and thus the impulsive force is very large, due to  which the body may damage.

So, when a person falls on the carpeted floor, there is a compression and thus, the time of contact is comparatively large and thus the impulsive force is small, due to  which the body may safe.

3 0
3 years ago
An apple falls from an apple tree growing on a 20° slope. The apple hits the ground with an impact velocity of 16.2 m/s straight
EleoNora [17]

Apple hits the surface with speed 16.2 m/s

The angle made by the apple velocity with normal to the incline surface is given as 20 degree

now the component of velocity which is parallel to the surface and perpendicular to the surface is given as

v_{perpendicular} = v cos20

v_{parallel} = v sin20

so here we have

v_{parallel} = 16.2 sin20

v_{parallel} = 5.5 m/s

<em>so its velocity along the incline plane will be 5.5 m/s</em>

7 0
3 years ago
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Answer:

Workdone = 465766038 Joules.

Explanation:

<u>Given the following data;</u>

Mass = 1167

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To find the workdone;

We know that from the workdone theorem, the workdone by an object or a body is directly proportional to the kinetic energy possessed by the object due to its motion.

Mathematically, it is given by the equation;

W = Kf - Ki

W = ½MVf² - ½MVi²

Substituting into the equation

W = ½(1167)*28² - ½(1167)*10²

W = ½ * 1361889* 784 - ½ * 1361889 * 100

W = 533860488 - 68094450

Workdone = 465766038 Joules.

7 0
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