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2 years ago

Acceleration is positive when you are speeding up.

Physics

1 answer:

Vikki [24]2 years ago

8 0

Answer:

B Negative

Explanation:

Its negative because when your going 25 mph your moving faster and when your coming up to the stop sign you will start to slow down going 10 mph then 0 mph when you reach the stop sign so it will be negative.

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A 5.0 kg box slides down a 4.0 m long ramp that makes a 25 angle with the ground. If the coefficient of kinetic friction is 0.65

Sedaia [141]

The thermal energy was produced is 116J

<h3>What is the thermal energy produced?</h3>

Now we know that the frictional force produces the energy that is lost as heat as the body slides down the incline. The magnitude of the frictional force is obtained from;

Ff= μmgcosθ

Ff = 0.65 * 5.0 kg * 9.8 m/s^2 * cos 25

Ff = 29 N

Hence, the thermal energy is;

29 N * 4.0 m = 116J

Learn more about frictional force:brainly.com/question/1714663

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4 0

2 years ago

A 256 Hz tuning fork is resonating in a closed tube on a warm day when the speed of sound is 346 m/s. What is the length of the

Ilya [14]

Assuming our "closed tube" is closed at only one end, then
 v = fλ = f*4L/n
 where "n" is the harmonic number. So
 L = nv / 4f = n*346m/s / 4*256Hz = n*0.38 m
 Since the only option in your list that is an integer multiple of 0.38 m is 1.35 m
 I'd say that we're hearing the fourth harmonic.
answer is
A. 1.35 m

5 0

3 years ago

g If 6.35 moles of a monatomic ideal gas at a temperature of 320 K are expanded isothermally from a volume of 1.45 L to a volume

vitfil [10]

Answer:

(a) change in the internal energy of the gas is zero

(b) the work done by the gas is 16.93 kJ

Explanation:

Given;

number of moles of gas, n = 6.35 moles

temperature of the gas, T = 320 K

initial volume of the gas, V₁ = 1.45 L

final volume of the gas, V₂ = 3.95 L

Part (a)

For isothermal expansion, temperature is constant and internal energy will also be constant.

Therefore, change in the internal energy of the gas is zero since the gas expanded isothermally (constant temperature).

ΔU = Q - W

where;

ΔU is change in internal energy

Q is heat transferred to the system

W is the work done by the system

Thus, Q = W

ΔU = 0

Part (b)

the work done by the gas

$W = nRTln{[\frac{V_2}{V_1}]$

where;

R is gas constant = 8.314 J/mol.K

$W = (6.35)(8.314)(320)ln{[\frac{3.95}{1.45}]}\\\\W =16930.4\ J\\\\W = 16.93\ kJ$

Part (c)

the heat flow into or out of the gas

Q = ΔU + W

Q = 0 + 16.93 kJ

Q = 16.93 kJ

Since the heat flow is positive, then it is heat flow into the gas.

3 0

3 years ago

What is the speed of a car that traveled 56 m in 4 seconds?

max2010maxim [7]

Answer:

$\boxed {\boxed {\sf 14 \ meters \ per \ second}}$

Explanation:

Speed is the rate of motion and can be found by dividing the distance by the time.

$s=\frac{d}{t}$

The distance covered is 56 meters and the time taken is 4 seconds.

$d= 56 \ m \\t= 4 \ s$

Substitute the values into the formula.

$s=\frac{56 \ m}{4 \ s}$

Divide.

$s= 14 \ m/s$

The speed of the car is 14 meters per second

3 0

3 years ago

Haley is driving down a straight highway at 73 mph. A construction sign warns that the speed limit will drop to 55 mph in 0.50 m

skad [1K]

Answer: $a= -1029.97 m/s^{2}$

Explanation:

We know Haley is driving with an initial velocity of $V_{o}=73mi/h$ and then she has to change to a velocity of $V_{f}=55mi/h$ in a distance $d=0.50 mi$ , and we also know we are dealing with constant acceleration $a$ .