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2 years ago

An object is moving east, and its velocity changes from 65 m/s to 25 m/s in 10 seconds Which describes the acceleration?

Physics

1 answer:

Rasek [7]2 years ago

8 0

Answer:

4 m/s in negative acceleration

Explanation:

Acceleration = V- U/t

Where V is the final velocity

U is the initial velocity and t is the time given.

U = 65 m/s

V= 25 m/s

T= 10 seconds

Acceleration= (25m/s - 65m/s)÷10secs

= - 40/10

= -4m/s^2

Hence, it has a negative acceleration.

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An unruly student with a spitwad (a lump of wet paper) of mass 20 g in his pocket finds himself in the school library where ther

jeka94

Answer:

T = 188.5 s, correct is C

Explanation:

This problem must be worked on using conservation of angular momentum. We define the system as formed by the fan and the paper, as the system is isolated, the moment is conserved

initial instant. Before the crash

L₀ = r m v₀ + I₀ w₀

the angular speed of the fan is zero w₀ = 0

final instant. After the crash

L_f = I₀ w + m r v

L₀ = L_f

m r v₀ = I₀ w + m r v

angular and linear velocity are related

v = r w

w = v / r

m r v₀ = I₀ v / r + m r v

m r v₀ = (I₀ / r + mr) v

v = $\frac{m}{\frac{I_o}{r} +mr} \ r v_o$

let's calculate

v = $\frac{0.020}{\frac{1.4}{0.6 } + 0.020 \ 0.6 } \ 0.6 \ 4$

v = $\frac{0.020}{2.345} \ 2.4$

v = 0.02 m / s

To calculate the time of a complete revolution we can use the kinematics relations of uniform motion

v = x / T

T = x / v

the distance of a circle with radius r = 0.6 m

x = 2π r

we substitute

T = 2π r / v

let's calculate

T = 2π 0.6/0.02

T = 188.5 s

reduce

t = 188.5 s ( 1 min/60 s) = 3.13 min

correct is C

6 0

2 years ago

What does the energy of an electromagnetic wave depend on?

Mrrafil [7]

It depends on frequency

6 0

2 years ago

Boyle's Law mainly involves _______.

goblinko [34]

Your answer is B, gases

6 0

3 years ago

From mechanics, you may recall that when the acceleration of an object is proportional to its coordinate, d2xdt2=−kmx=−ω2x , suc

marysya [2.9K]

Answer:

q = q₀ sin (wt)

Explanation:

In your statement it is not clear the type of circuit you are referring to, there are two possibilities.

1) The circuit of this problem is a system formed by an Ac voltage source and a capacitor, in this case all the voltage of the source is equal to the voltage at the terminals of the capacitor

ΔV = Δ $V_{C}$

we assume that the source has a voltage of the form

ΔV = ΔV₀o sin wt

The capacitance of a capacitor is

C = q / ΔV

q = C ΔV sin wt

the current in the circuit is

i = dq / dt

i = c ΔV₀ w cos wt

if we use

cos wt = sin (wt + π / 2)

we make this change by being a resonant oscillation

we substitute

i = w C ΔV₀ sin (wt + π/2)

With this answer we see that the current in capacitor has a phase factor of π/2 with respect to the current

2) Another possible circuit is an LC circuit.

In this case the voltage alternates between the inductor and the capacitor

V_{L} + V_{C} = 0

L di / dt + q / C = 0

the current is

i = dq / dt

they ask us for a solution so that

L d²q / dt² + 1 / C q = 0

d²q / dt² + 1 / LC q = 0

this is a quadratic differential equation with solution of the form

q = A sin (wt + Ф)

to find the constant we derive the proposed solution and enter it into the equation

di / dt = Aw cos (wt + Ф)

d²i / dt²= - A w² sin (wt + Ф)

- A w² + 1 /LC A = 0

w = √ (1 / LC)

To find the phase factor, for this we use the initial conditions for t = 0

in the case of condensate for t = or the charge is zero

0 = A sin Ф

Ф = 0

q = q₀ sin (wt)

6 0

2 years ago

You push a coin across a table. The coin stops. How does this motion relate to balanced and unbalanced forces?

Snezhnost [94]

If you are pushing the coin across the table at a constant rate, the friction of the table and the horizontal force of your hand pushing are equal, and the coin itself moves at a constant rate. If you push a coin and let it go, there is no horizontal force keeping the coin going. Friction slows the coin to a stop. In both cases, the gravitational downward pull of Earth is equally but oppositely resisted by the upward push of table on the coin.

7 0

2 years ago