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Ymorist [56]
3 years ago
14

A car accelerates uniformly from 10 m/s to 20 m/s in 4.2 seconds. what is the magnitute of its acceleration

Physics
2 answers:
oksian1 [2.3K]3 years ago
8 0

Connexus Physics pre-ap semester A final exam, all correct answers. And y’all better be freaking grateful, because it took a long time to type all this out.

<span>1)      </span>In the steps of the scientific method…
A. Interpreting results

<span>2)      </span>The radius of the Earth is…
B. 6.37 x 10^3 km

<span>3)      </span>Which of the following equations best describes…
D. y = 1/2x

<span>4)      </span>In the graph, what is the correct description…
C. Negative position

<span>5)      </span>The motion of a ball on an inclined plane is described…
C. vi

<span>6)      </span>Acceleration due to gravity is also called
C. free-fall acceleration

<span>7)      </span>Which of the following is a physical quantity…
A. vector

<span>8)      </span>In a coordinate system, a vector is…
A. Cos (theta)

<span>9)      </span>Which of the following is an example of projectile motion?
B. a thrown baseball

<span>10)   </span>A newton is equivalent to which…
A. kg * m/s^2

<span>11)   </span>In the free-body diagram shown below, which of the following…
C. 4050 N

<span>12)   </span>A net force of 6.8 N accelerates a 31 kg scooter…
A. 0.22 m/s^2

<span>13)   </span>A change in the gravitational force acting…
C. Weight

<span>14)   </span>A passenger on a bus moving east sees a man standing on a curb…
C. move west at a speed that is equal to the bus’s speed.

<span>15)   </span>In which of the following scenarios is no net work done?
B. A car travels at a constant speed on a flat road.

<span>16)   </span>What is the kinetic energy of a 0.135 kg baseball thrown at 40.0 m/s?
C. 108 J

<span>17)   </span>Which of the following refers to the sum of kinetic energy…
D. mechanical energy

<span>18)   </span>Which of the following are not units of power?
B. J

<span>19)   </span>Which of the following…can be used to…calculate…change in…momentum?
D. (delta)p = F (delta) t

<span>20)   </span>Two skaters stand facing…
B. their momenta are equal but opposite.

<span>21)   </span>In an inelastic collision…
D. the momentum of one object will increase by the amount that the momentum of the other object decreases.

<span>22)   </span>When an object is moving with uniform circular motion…tangential speed
C. is constant

<span>23)   </span>Which units would be the most appropriate to use to…
A. newtons

<span>24)   </span>How would the speed of Earth’s orbit around the sun change…
A. The speed would not change

<span>25)   </span>A girl pushes a box that has a weight of 450 N up an incline…force of 150 N along…
B. 3.0

<span>26)   </span>According to the law of conservation of mechanical energy,
C. Total energy must remain the same

<span>27)   </span>The potential energy of a 60 kg man…balcony 43 meters…
A. 25000 J

<span>28)   </span>If two small beakers of water, one at 70C and one at 80C…
C. The final temperature is between 70C and 80C

<span>29)   </span>Why does sandpaper get hot when it is rubbed against rusty metal?
C. Friction between the sandpaper and metal…

<span>30)   </span>Which of the following describes a substance in which the temperature and pressure…
D. substance undergoing a change of state

<span>31)   </span>An ideal gas system is maintained at a constant volume of 4 L. If pressure is constant…
A. 0 J

<span>32)   </span>Which of the following is a thermodynamic process in which a system…
C. a cyclic process

<span>33)   </span>When a drop of ink mixes with water…
A The system’s entropy increases, and the total entropy of the universe increases.

<span>34)   </span>A mass-spring system can oscillate…
D. elastic potential

<span>35)   </span>If a semi-truck decrease its speed from 10 m/s to 5 m/s...
D. ¼ its old kinetic energy

<span>36)   </span>A boy releases a small 1 kg toy truck from rest down a 5 meter high hill…
B. 50 J

<span>37)   </span>A car accelerates uniformly from 10 m/s to 20 m/s in 4.2 seconds…
A. 2.4 m/s^2

<span>38)   </span>What must the minimum tension of a single vertical wire be to support a 1.5 kg picture?
A. 15 N

<span>39)   </span>Why does it seem harder to start sliding a couch across a carpeted floor than…
C. The opposing force of friction is greater when an object starts from rest…

<span>40)   </span>An elevator weighing 2.00 c 10^5 N is supported by a steel cable…
Fw =  mass * gravitational acceleration
2*10^5 = mass * 9.8
mass of the elevator = 20.4*10^3 kg

Fnet = Tension – Fw
mass * acceleration = Tension – 2*10^5
20.4*10^3 * 3 = Tension – 2*10^5
61200 = Tension – 2*10^5
Tension = (61200) + (2*10^5)
Tension = 2.61 * 10^5 newton

<span>41)   </span>A bullet with a mass of 6.00 g is fired through a 1.25 kg block of wood on a frictionless surface.
0.006(896) + 0 = 0.006(435) + 1.25(V)
5.376 + 0 = 2.61 + 1.25(V)
5.376 = 2.61 + 1.25(V)
2.766 = 1.25(V)
V = 2.21 m/s

<span>42)   </span>Find the final equilibrium temperature when 10.0 g of milk at 10.0C is added to 1.60 x 10^2 g of coffee with a temperature of 90.0C.
Heat lost = heat gained
X = equilibrium temperature
Heat lost = 160(90-x)
Heat gained = 10(x-10)
14400 – 160x = 10x -100
170x = 14500
X = 14500/170
X = 85.25 degrees





Dafna1 [17]3 years ago
6 0
A=Vf-Vi/t
a=20m/s-10m/s/4.2s
a=2.4m/s^2
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Explanation:

It is given that,

Mass of the car, m = 1000 kg

Speed of the car, v = 100 km/h = 27.77 m/s

The coefficient of kinetic friction of the tires, \mu_k=0.5

Let f is the net force acting on the body due to frictional force, such that,

-f=ma

a=\dfrac{-f}{m}

a=\dfrac{-\mu _k mg}{m}

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We know that the acceleration of the car in calculus is given by :

v.dv=a.dx, x is the stopping distance

\int\limits^0_v {v.dv}=\int\limits^x_0 {a.dx}

\dfrac{v^2}{2}|_v^0=ax

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On solving the above equation, we get, x = 78.69 meters

So, the stopping distance for the car is 78.69 meters. Hence, this is the required solution.

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-The indicator changes color over a pH range from 6.0 (yellow) to 7.6 (blue). It is a good indicator of dissolved carbon dioxide (CO2) and other weakly acidic solutions.

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