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bazaltina [42]
3 years ago
12

A student is late and running to class. A hall monitor tells them to slow down, so the student slows to a walking speed of 1.4 m

/s. It takes the student 3.0 seconds to slow to this speed, due to the student’s -2.5 m/s2 acceleration. What was the student’s initial speed
Physics
1 answer:
sergey [27]3 years ago
7 0

Answer:

8.9m/s

Explanation:

Final velocity = initial velocity + acceleration *time

Vf=vi+at

Vf=1.4 m/s

Vi=?

A=-2.5m/s^2

T=3

1.4m/s=vi+(-2.5m/s^2)(3s)

Vi=8.9m/s

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A motorcycle is following a car that is traveling at a constant speed on a straight highway. Initially, the car and the motorcyc
Artist 52 [7]

Answer:

(a) 3.807 s

(b) 145.581 m

Explanation:

Let Δt = t2 - t1 be the time it takes from the moment when the motorcycle starts to accelerate until it catches up with the car. We know that before the acceleration, both vehicles are travelling at a constant speed. So they would maintain a distance of 58 m prior to the acceleration.

The distance traveled by car after Δt (seconds) at v_c = 23m/s speed is

s_c = \Delta t v_c = 23\Delta t

The distance traveled by the motorcycle after Δt (seconds) at m_m = 23 m/s speed and acceleration of a = 8 m/s2 is

s_m = \Delta t v_m + a\Delta t^2/2

s_m = 23\Delta t + 8\Delta t^2/2 = 23 \Delta t + 4 \Delta t^2

We know that the motorcycle catches up to the car after Δt, so it must have covered the distance that the car travels, plus their initial distance:

s_m = s_c + 58

23 \Delta t + 4 \Delta t^2 = 23\Delta t + 58

4 \Delta t^2 = 58

\Delta t^2 = 14.5

\Delta t = \sqrt{14.5} = 3.807s

(b)

s_m = 23 \Delta t + 4 \Delta t^2

s_m = 23*3.807 + 58 = 145.581 m

5 0
3 years ago
Energy can be changed from one form to another. Which terms can be used to describe these changes? Select all that apply.
aliya0001 [1]

Energy is the capacity to do work. Energy exists in various forms in the entire universe.

It  may be light,sound,electric,magnetic,kinetic,potential,thermal energy etc.

As per the law of conservation of energy, it is neither created not destroyed. It can change from one form to another form.The total energy of the universe is always constant.

The process in which energy will change from one form to another form is called energy conversion.

There is also another terminology for energy conversion called energy transformation.

Energy transference is the process in which energy will be transferred from one body to another body.

Hence the correct answer to this question will be conversion and transformation

5 0
4 years ago
Read 2 more answers
Determine the magnitude and direction of the resultant velocity of 75.0 m/s. 25.0 east of north, and 100.0 m/s, 25.0 east of sou
aleksandr82 [10.1K]

Answer:

77.35 m / s

Ф = -17° from + X axis or 343° from + X axis

Explanation:

v1 = 75 m/s 25° east of north

v2 = 100 m/s  25° east of south

Write the velocities in vector form ,we get

\overrightarrow{v_{1}}=75\left ( Sin25\widehat{i} +Cos25\widehat{j}\right )=31.7\widehat{i}+67.97\widehat{j}

\overrightarrow{v_{1}}=100\left ( Sin25\widehat{i} -Cos25\widehat{j}\right )=42.26\widehat{i}-90.63\widehat{j}

Now add the velocity vectors to get the resultant of the velocities.

\overrightarrow{v}=\overrightarrow{v_{1}}+\overrightarrow{v_{2}}

\overrightarrow{v}=\left (31.7+42.26  \right )\widehat{i}+\left ( 67.97- 90.63 \right )\widehat{j}

\overrightarrow{v}=73.96\widehat{i}-22.66\widehat{j}

magnitude of resultant velocity is \sqrt{\left ( 73.96 \right )^{2}+\left ( -22.66 \right )^{2}}

  = 77.35 m / s

The direction is Ф from X axis

tan\phi =\frac{-22.66}{73.96}=-0.306

Ф = -17° from + X axis or 343° from + X axis

7 0
4 years ago
The diagrams show vectors. Which diagram represents the vector addition C = A
rewona [7]

Answer:

C

Explanation:

good luck :3

8 0
4 years ago
Which of the following refers to the increasing size of deserts worldwide? A. disintegration B. desertification C. decomposition
algol [13]
 the answer is   B. desertification 
7 0
4 years ago
Read 2 more answers
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