Ask question

Ask question

All categories

2 years ago

12

A car traveling at a speed of 30.0 m/s encounters an emergency and comes to a complete stop. how much time will it take for the

car to stop if it decelerates at -4.0 m/s2

1 answer:

Vedmedyk [2.9K]2 years ago

8 0

Answer:7.5seconds

Explanation:

V=0 u=30m/s a=-4m/s^2

t=(v-u)/a

t=(0-30)/-4=-30/-4

t=7.5second

You might be interested in

What is the speed of gravity

mojhsa [17]

9.8m per seccond is the speed of gravity if you drop something like a ball from a tower

8 0

3 years ago

Please tell me if this is Newton's first law, second, or third law of motion. There can be more than one of the same answer very

AfilCa [17]

Answer: Hope This Helps!

Explanation:

1: Newton’s first law of motion can explain how a magician pulls a tablecloth from underneath the dishes. A negligible horizontal force is applied during the process. As per Newton’s first law of motion, the dishes and glasses remain in their state of motion (rest); as a result, they remain undisturbed.

2: Newton's First Law of Motion is defined as "An object at rest and an object in motion will stay in motion with the same speed and in the same direction unless acted upon by an unbalanced force."In soccer, when the soccer ball is in the soccer field and it is not moving, that means that it is at rest and there is no force acting upon it. When there is a person that is ready to play soccer and wants to kick the ball and play, then the unbalanced force would be the power from the person's foot.

3: Newtons third law can explain, as the cannonball is pushed forwards by the expanding high-pressure gases created by the exploding gunpowder, it pushes back on these gases. The gases push back on the cannon itself, causing it to roll backwards. Alternative answer: the cannon pushes forward on the cannonball. the reaction force is the cannonball pushing backwards on the cannon.

5 0

3 years ago

Say that you are in a large room at temperature TC = 300 K. Someone gives you a pot of hot soup at a temperature of TH = 340 K.

DiKsa [7]

Answer:0.061

Explanation:

Given

$T_C=300 k$

Temperature of soup $T_H=340 K$

heat capacity of soup $c_v=33 J/K$

Here Temperature of soup is constantly decreasing

suppose T is the temperature of soup at any instant

efficiency is given by

$\eta =\frac{dW}{Q}=1-\frac{T_C}{T}$

$dW=Q(1-\frac{T_C}{T})$

$dW=c_v(1-\frac{T_C}{T})dT$

integrating From $T_H$ to $T_C$

$\int dW=\int_{T_C}^{T_H}c_v(1-\frac{T_C}{T})dT$

$W=\int_{T_C}^{T_H}33\cdot (1-\frac{300}{T})dT$

$W=c_v\left [ T-T_C\ln T\right ]_{T_H}^{T_C}$

$W=c_v\left [ \left ( T_C-T_H\right )-T_C\left ( \ln \frac{T_C}{T_H}\right )\right ]$

Now heat lost by soup is given by

$Q=c_v(T_C-T_H)$

Fraction of the total heat that is lost by the soup can be turned is given by

$=\frac{W}{Q}$

$=\frac{c_v\left [ \left ( T_C-T_H\right )-T_C\left ( \ln \frac{T_C}{T_H}\right )\right ]}{c_v(T_C-T_H)}$

$=\frac{T_C-T_H-T_C\ln (\frac{T_C}{T_H})}{T_C-T_H}$

$=\frac{300-340-300\ln (\frac{300}{340})}{300-340}$

$=\frac{-40+37.548}{-40}$

$=0.061$

4 0

2 years ago

Which of the following changes would make a heat engine less efficient

DIA [1.3K]

A heat engine would be less efficient due to many factors
For instance, a heat engine is more efficient when it uses in cold weather because there is a greater temperature difference ( Carnot Efficient )
A heat engine could be less efficient because of friction
Hope it helps I am a beginner

8 0

3 years ago

A soccer ball is rolling with a constant acceleration of -1.5 m/s2 . At ti = 0 s, the ball has an instantaneous velocity of 14 m

miskamm [114]

Answer:

$v_{f} = 9.5\,\frac{m}{s}$

Explanation:

The final velocity is:

$v_{f} = v_{o} + a \cdot t$

$v_{f} = 14\,\frac{m}{s} + (-1.5\,\frac{m}{s^{2}} )\cdot (3\,s)$

$v_{f} = 9.5\,\frac{m}{s}$

6 0

2 years ago