A car that travels 200 miles North in 4 hours. What is the velocity of the in miles per hour?

A car travels a distance of 100 km. For the first 30 minutes it is driven at a constant speed of 80 km/hr. The motor begins to v

gregori [183]

Explanation:

First, we need to determine the distance traveled by the car in the first 30 minutes, $d_{\frac{1}{2}}$ .

Notice that the unit measurement for speed, in this case, is km/hr. Thus, a unit conversion of from minutes into hours is required before proceeding with the calculation, as shown below

$d_{\frac{1}{2}\text{h}} \ = \ \text{speed} \ \times \ \text{time taken} \\ \\ \\ d_{\frac{1}{2}\text{h}} \ = \ 80 \ \text{km h}^{-1} \ \times \ \left(\displaystyle\frac{30}{60} \ \text{h}\right) \\ \\ \\ d_{\frac{1}{2}\text{h}} \ = \ 80 \ \text{km h}^{-1} \ \times \ 0.5 \ \text{h} \\ \\ \\ d_{\frac{1}{2}\text{h}} \ = \ 40 \ \text{km}$

Now, it is known that the car traveled 40 km for the first 30 minutes. Hence, the remaining distance, $d_{\text{remain}}$ , in which the driver reduces the speed to 40km/hr is

$d_{\text{remain}} \ = \ 100 \ \text{km} \ - \ 40 \ \text{km} \\ \\ \\ d_{\text{remain}} \ = \ 60 \ \text{km}$ .

Subsequently, we would also like to know the time taken for the car to reach its destination, denoted by $t_{\text{remian}}$ .

$t_{\text{remain}} \ = \ \displaystyle\frac{\text{distance}}{\text{speed}} \\ \\ \\ t_{\text{remain}} \ = \ \displaystyle\frac{60 \ \text{km}}{40 \ \text{km hr}^{-1}} \\ \\ \\ t_{\text{remain}} \ = \ 1.5 \ \text{hours}$ .

Finally, with all the required values at hand, the average speed of the car for the entire trip is calculated as the ratio of the change in distance over the change in time.

$\text{speed} \ = \ \displaystyle\frac{\Delta d}{\Delta t} \\ \\ \\ \text{speed} \ = \ \displaystyle\frac{100 \ \text{km}}{(0.5 \ \text{hr} \ + \ 1.5 \ \text{hr})} \\ \\ \\ \text{speed} \ = \ \displaystyle\frac{100 \ \text{km}}{2 \ \text{hr}} \\ \\ \\ \text{speed} \ = \ 50 \ \text{km hr}^{-1}$

Therefore, the average speed of the car is 50 km/hr.

8 0

3 years ago

A 50.0 kg driver is riding at 35.0 m/s in her red sports car when she must suddenly slam on the brakes to avoid

egoroff_w [7]

Answer:

3500N

Explanation:

Given parameters:

Mass of driver = 50kg

Speed = 35m/s

Time = 0.5s

Unknown:

Average force the seat belt exerts on her = ?

Solution:

The average force the seat belt exerts on her can be deduced from Newton's second law of motion.

F = mass x acceleration

So;

F = mass x $\frac{change in velocity }{time}$

F = 50 x $\frac{35}{0.5}$ = 3500N

8 0

3 years ago

Write two examples of machine which changes the direction of force

Ostrovityanka [42]

Answer:

Washign machine and swingset

Explanation:

4 0

3 years ago

What are the seven types of electromagnetic waves?

Sunny_sXe [5.5K]

Radio waves. Giant satellite-dish antennas pick up long-wavelength, high-frequency radio waves. ...
Microwaves. Because cosmic microwaves can't get through the whole of Earth's atmosphere, we have to study them from space. ...
Infrared. ...
Visible light. ...
Ultraviolet light. ...
X rays. ...
Gamma rays.

5 0

3 years ago

Describe ehat happens at the molecular level during meilting

Marta_Voda [28]

The molecules of a solid vibrate faster so that they start spreading out to become a liquid. This energy makes them vibrate faster so the bonds between molecules can't interact all that well anymore creating more distance. The stronger the bonds between the molecules the higher the energy (temperature) has to be to get them away from each other. Hope I didn't confuse you too much!

3 0

3 years ago