Ask question

Ask question

All categories

2 years ago

5

A car advertisement states that a car can accelerate at 2 m/sec. The car starts from rest and accelerates to 70 km/hr. How much

time does it take to accelerate to 70 km/hr.

1 answer:

Reptile [31]2 years ago

7 0

Answer:

9.72s

Explanation:

$\pink{\frak{Given}}\begin{cases}\textsf{ A car starts from rest.}\\\textsf{It has an acceleration of 2m/s$^2$.}\\\textsf{ The final velocity of the car is 70km/hr.}\end{cases}$

Here we need to find out the time that the car took to achieve the velocity of 70km/hr after starting from rest . Firstly convert the final velocity in m/s by multiplying it by 5/18 , as ,

$\longrightarrow\sf 70km/hr = 70 \times \dfrac{5}{18} m/s =\bf 19.44\ m/s$

As we know that the rate of change of velocity is known as acceleration , so ;

$\longrightarrow\sf a =\dfrac{v - u}{t}$

Plug in the respective values ,

$\longrightarrow\sf 2m/s^2 = \dfrac{ 19.4 m/s -0m/s}{t} \\$

Simplify ,

$\longrightarrow\sf 2m/s^2 =\dfrac{19.4m/s}{t}$

Cross multiply ,

$\longrightarrow\sf t = \dfrac{19.44m/s}{2m/s^2}$

Simplify

$\longrightarrow\sf \boxed{\bf t = 9.72 s}$

<h3>Hence the required answer is 9.72s.</h3>

You might be interested in

You drop your frozen rock from a green bridge. The frozen rock starts from rest (initial velocity = 0ms). The rock takes 4.3s to

valentinak56 [21]

Answer:

The velocity of the frozen rock at $t = 1.5\,s$ is -14.711 meters per second.

Explanation:

The frozen rock experiments a free fall, which is a type of uniform accelerated motion due to gravity and air viscosity and earth's rotation effect are neglected. In this case, we need to find the final velocity ( $v$ ), measured in meters per second, of the frozen rock at given instant and whose kinematic formula is:

$v = v_{o} + g\cdot t$ (Eq. 1)

Where:

$v_{o}$ - Initial velocity, measured in meters per second.

$g$ - Gravity acceleration, measured in meters per square second.

$t$ - Time, measured in seconds.

If we get that $v_{o} = 0\,\frac{m}{s}$ , $g = -9.807\,\frac{m}{s^{2}}$ and $1.5\,s$ , then final velocity is:

$v = 0\,\frac{m}{s}+\left(-9.807\,\frac{m}{s^{2}} \right) \cdot (1.5\,s)$

$v = -14.711\,\frac{m}{s}$

The velocity of the frozen rock at $t = 1.5\,s$ is -14.711 meters per second.

5 0

2 years ago

What kind of relationship does a human have with the bacteria that lives in her/his digestive tract?

Misha Larkins [42]

The one that both benefits each other is the one I think it's mutalistic

4 0

3 years ago

What type of circuit is seen in this picture?<br><br> -Open<br> -Parallel<br> -Series<br> -AC

MA_775_DIABLO [31]

it's a. open circuit

3 0

3 years ago

Read 2 more answers

How does battery generate electric current in a circuit?

sveticcg [70]

Answer:

C. It creates negative electric charges and pushes them into the circuit

Explanation:

A battery has three main parts. The Cathode (Positive), the Electrolytes (energy source), and the Anode (negative). The anode takes energy from the electrolytes and creates more electrons. And because subatomic particles with the same charge don't like being in the same place, they move through the circuit to reach the cathode because opposites attract.

I hope this helps!

3 0

3 years ago

Near the top of the Citigroup Center building in New York City, there is an object with mass of 4.00 ✕ 105 kg on springs that ha

jasenka [17]

Explanation:

It is given that,

Mass of an object, $m=4\times 10^5\ kg$

(a) Time period of oscillation, T = 2.4 s

The formula for the time period of spring is given by :

$T=2\pi \sqrt{\dfrac{m}{k}}$

Where

k is the force constant

$k=\dfrac{4\pi ^2 m}{T^2}$

$k=\dfrac{4\pi ^2 \times 4\times 10^5}{(2.4)^2}$

$k=2.74\times 10^6\ N/m$

(b) Displacement in the spring, x = 2.2 m

Energy stored in the spring is given by :

$U=\dfrac{1}{2}kx^2$

$U=\dfrac{1}{2}\times 2.74\times 10^6\ N/m\times (2.2\ m)^2$

$U=6.63\times 10^6\ J$

Hence, this is the required solution.

7 0

3 years ago