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3 years ago

Grade 10 My smart Physics people help me with this review question please

Physics

1 answer:

Kaylis [27]3 years ago

3 0

Answer: a = 1, b = 9, c = 6, d = 4

Explanation:

With no velocity, total mechanical energy is all gravity potential energy

PE = mgh = 80.0(9.81)(25) = 19,620 J = 1.96e4 J

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As a result of friction, the angular speed of a wheel changes with time according to dθ/dt = ω0e^−σt where ω0 and σ are constant

NNADVOKAT [17]

Hi there!

We can use the initial conditions to solve for w₀.

It is given that:

$\frac{d\theta}{dt} = w_0e^{-\sigma t}$

We are given that at t = 0, ω = 3.7 rad/sec. We can plug this into the equation:

$\omega(0)= \omega_0e^{-\sigma (0)}\\\\3.7 = \omega_0 (1)\\\\\omega_0 = \boxed{3.7 rad/sec}$

Now, we can solve for sigma using the other given condition:

$2 = 3.7e^{-\sigma (8.6)}\\\\.541 = e^{-\sigma (8.6)}\\\\ln(.541) = -\sigma (8.6)\\\\\sigma = \frac{ln(.541)}{-8.6} = \boxed{0.0714s^{-1}}$

The angular acceleration is the DERIVATIVE of the angular velocity function, so:

$\alpha(t) = \frac{d\omega}{dt} = -\sigma\omega_0e^{-\sigma t}\\\\\alpha(t) = -(0.0714)(3.7)e^{-(0.0714) (3)}\\\\\alpha(t) = \boxed{-0.213 rad\sec^2}$

The angular displacement is the INTEGRAL of the angular velocity function.

$\theta (t) = \int\limits^{t_2}_{t_1} {\omega(t)} \, dt\\\\\theta(t) = \int\limits^{2.5}_{0} {\omega_0e^{-\sigma t}dt\\\\$

$\theta(t) = -\frac{\omega_0}{\sigma}e^{-\sigma t}\left \| {{t_2=2.5} \atop {t_1=0}} \right.$

$\theta = -\frac{3.7}{0.0714}e^{-0.0714 t}\left \| {{t_2=2.5} \atop {t_1=0}} \right. \\\\\theta= -\frac{3.7}{0.0714}e^{-0.0714 (2.5)} + \frac{3.7}{0.0714}e^{-0.0714 (0)}$

$\theta = 8.471 rad$

Convert this to rev:

$8.471 rad * \frac{1 rev}{2\pi rad} = \boxed{1.348 rev}$

We can begin by solving for the time necessary for the angular speed to reach 0 rad/sec.

$0 = 3.7e^{-0.0714t}\\\\t = \infty$

Evaluate the improper integral:

$\theta = \int\limits^{\infty}_{0} {\omega_0e^{-\sigma t}dt\\\\$

$\lim_{a \to \infty} \theta = -\frac{\omega_0}{\sigma}e^{-\sigma t}\left \| {{t_2=a} \atop {t_1=0}} \right.$

$\lim_{a \to \infty} \theta = -\frac{3.7}{0.0714}e^{-0.0714a} + \frac{3.7}{0.0714}e^{-0.0714(0)}\\\\ \lim_{a \to \infty} \theta = \frac{3.7}{0.0714}(1) = 51.82 rad$

Convert to rev:

$51.82 rad * \frac{1rev}{2\pi rad} = \boxed{8.25 rev}$

8 0

3 years ago

Suppose that Lisa walks her dog around the block for a little exercise. The block is 1 mile around. If she walks around the bloc

natita [175]

Displacement only measure how far between the starting and ending point. In this case, Lisa walks around the block as a circle so the starting point is the same as the ending point. Thus, displacement is 0mile.
On the other hand, distance measures exactly how far she walks. In this case, the distance is 1 mile, same as the perimeter of the block.

7 0

3 years ago

Two identical 0.50-kg carts, each 0.10 m long, are at rest on a low-friction track and are connected by a spring that is initial

Keith_Richards [23]

Answer:

The system's kinetic energy changes by 3.6 J

Explanation:

The given parameters are;

The number of cart = 2

The mass of each cart = 0.5kg

The initial length of the spring = 0.50 m

The final length of the spring =T0.3 m

The change in position of the first cart = 0.6 m

The energy given to the first cart = Work done by the force = Force × Displacement

The initial kinetic energy of the two cart moving together = Energy given to the first cart = 6.0 × 0.2 = 1.2J

The kinetic energy given to the two cart combined = The applied force × The total displacement of the two cart as they move together

The kinetic energy given to the two cart combined = 6.0 × (0.6 - 0.2)

The kinetic energy given to the two cart combined = 6.0 × 0.4 = 2.4 J

The total kinetic energy given to the two cart = 1.2 + 2.4 = 3.6 J

The total kinetic energy given to the two cart = 3.6 J

The system's kinetic energy changes by 3.6 J.

8 0

3 years ago

Use the circuit diagram to decide if the lightbulb will light. Justify your answer

elena-14-01-66 [18.8K]

Answer:

It will.

Explanation:

For a circuit to function properly, everything has to be connected. As the diagram shows that everything is connected and there are no gaps, it will light.

3 0

3 years ago

Read 2 more answers

Plzz answer this question correctly

Leno4ka [110]

Answer:

by reducing friction.....

6 0

3 years ago