All categories

3 years ago

A motorcyclist drove 7 km at 57km/h and then another 7 km at 81 km/h. What was the average speed?

Physics

1 answer:

alex41 [277]3 years ago

7 0

Answer:

The average speed of the car is 66.9 km/h

Explanation:

Here distance covered with the speed 57 km/h=7 km 

distance covered with the speed of 81 km/h=7 km

Average speed is equal to the ratio of total distance to the total time.

total distance= 7 + 7= 14 km

$time= \frac{distance}{speed}$

time taken to cover the first 7 km= 7/57 h

time taken to cover the second part of the journey = 7/81 h

average speed = $14/(7/57+7/81)=(14 \times 57 \times 81)/945=66.9 km/h$ 

Shortcut: 

When equal distances are covered with different speeds average speed=2 ab/(a+b) where a and b are the variable speeds in the phases. 

You might be interested in

You need to make a very dilute solution of sodium phosphate dihydrate (MW 142 g/mol, FW 178 g/mol). How many grams of sodium pho

dlinn [17]

Answer:

first question is 178 g of sodium phosphate dihydrate. second question is 0.25 mL

Explanation:

To know the number of grams from the number of moles $(0.5L*2mol/L)= 1mol$ . 1 mol is equal to 178 g. Second question mL of the stock is obtained from $(0.1L*5.0^-3mol/L)/2mol/L$ .

6 0

3 years ago

What condition is necessary for an object to make a good reference point?

777dan777 [17]

The object is fixed relative to the motion you are trying to describe.

8 0

4 years ago

Eat the majority of your calories in the evening to fuel your sleep hou True False

Nataliya [291]

Answer: false

Explanation:

because

7 0

3 years ago

Read 2 more answers

You're driving a vehicle of mass 1350 kg and you need to make a turn on a flat road. The radius of curvature of the turn is 71 m

sergey [27]

Answer:

$v=12.65\ m.s^{-1}$

Explanation:

Given:

mass of vehicle, $m=1350\ kg$

radius of curvature, $r=71\ m$

coefficient of friction, $\mu=0.23$

During the turn to prevent the skidding of the vehicle its centripetal force must be equal to the opposite balancing frictional force:

$m.\frac{v^2}{r} =\mu.N$

where:

$\mu=$ coefficient of friction

$N=$ normal reaction force due to weight of the car

$v=$ velocity of the car

$1350\times \frac{v^2}{71} =0.23\times (1350\times 9.8)$

$v=12.65\ m.s^{-1}$ is the maximum velocity at which the vehicle can turn without skidding.

5 0

3 years ago

the force exerted by gravity,electricity,and magnetism act at a distance with no physical connection. for this reason, they are

Soloha48 [4]

Its called the electric force

7 0

3 years ago

Read 2 more answers

A motorcyclist drove 7 km at 57km/h and then another 7 km at 81 km/h. What was the average speed? ​

A motorcyclist drove 7 km at 57km/h and then another 7 km at 81 km/h. What was the average speed?