##### physics question

A toy car with a mass of 1 kg starts from rest at the top of a ramp at point A. The toy car is released from rest, rolls 2.0 meters down the ramp, then another 3.0 meters across the floor to point B where its speed is measured to be 4.24 m/s. The air exerts a resistance force of 2.0 N on the car as it moves from A to B. Find the initial height of the car at point A. Assume g = 10 m/s^2.

Note: The user has mastered the concept of the conservation of energy and is proficient in solving problems where energy is conserved but is new to solving energy problems involving work done by non-conservative forces. Explain how work is related to the total mechanical energy of a system, then use this information to set up and solve the problem above.

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##### How far does the pendulum bob (the ball at the end of the rope) travel in one complete cycle of motion if its length is 32.7 cm?

A pendulum (shown in the figure) sweeps out an angle of 22.7° during its motion. How far does the pendulum bob (the ball at the end of the rope) travel in one complete cycle of motion if its length is 32.7 cm?

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##### Find the time th it takes the projectile to reach its maximum height H. Express th in terms of v0, theta, and g (the magnitude of the acceleration due to gravity).

Find the time th it takes the projectile to reach its maximum height H. Express th in terms of v0, theta, and g (the magnitude of the acceleration due to gravity). Find tR, the time at which the projectile hits the ground after having traveled through a horizontal distance R. Express the time in terms of v0, theta, and g. Find H, the maximum height attained by the projectile. Express the time in terms of v0, theta, and g. Find the total distance R (often called the range) traveled in the x direction; see the figure in the problem introduction.

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##### You begin sliding down a 15 ski slope. Ignoring friction and air resistance, how fast will you be moving after 10?

You begin sliding down a 15 ski slope. Ignoring friction and air resistance, how fast will you be moving after 10?

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##### An electric eel develops a potential difference of 500 V, driving a current of 0.90 A for a 1.0 ms pulse.

An electric eel develops a potential difference of 500 V, driving a current of 0.90 A for a 1.0 ms pulse.
A.Find the power of this pulse.
B. Find the total energy of this pulse.
C.Find the total charge that flows during the pulse.

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##### A 85 W electric blanket runs at 24 V .

A 85 W electric blanket runs at 24 V .

What is the resistance of the wire in the blanket?
How much current does the wire carry?

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##### A cell membrane has a resistance and a capacitance and thus a characteristic time constant.

What is the time constant of a 9.0-nm-thick membrane surrounding a 0.040-mm-diameter spherical cell? Assume the resistivity of the cell membrane as 3.6×107 ??m and the dielectric constant is approximately 9.0.

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##### A person will feel a shock when a current of greater than approximately 100 μA flows between his index finger and thumb.

A person will feel a shock when a current of greater than approximately 100 μA flows between his index finger and thumb.

If the resistance of dry skin is 200 times larger than the resistance of wet skin, how do the maximum voltages without shock compare in each scenario?

 A The voltage on dry skin needs to be 200 times smaller than the voltage on wet skin. B The voltage on dry skin needs to be 200 times larger than the voltage on wet skin. C The voltage on dry skin is the same as the voltage on wet skin. D The voltage on dry skin needs to be 40,000 times larger than the voltage on wet skin.

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##### Consider the circuit shown in the following figure. The battery has emf 50.0 V and negligible internal resistance.

Consider the circuit shown in the following figure. The battery has emf 50.0 V and negligible internal resistance. R2 = 3.00 Ω, C1= 3.00 μF, and C2= 6.00 μF. After the capacitors have attained their final charges, the charge on C1 is Q1 = 15.0 μC.

A) What is the final charge on C2?

B) What is the resistance R1?

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##### A capacitor is discharged through a 30 resistor.

A capacitor is discharged through a $$30{\Omega}$$ resistor. The discharge current decreases to27 $${\%}$$ of its initial value in $$1.7 \mathrm{~ms}$$. What is the value of the capacitor in $$\mu F ?$$ Express your answer using two significant figures.

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##### How long does it take to reduce the capacitor's charge to 5.00 µC?

A 10.0 µF capacitor initially charged to 30.0 µC is discharged through a 1.50 kO resistor. How long does it take to reduce the capacitor's charge to 5.00 µC?

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##### The voltage across each resistor in the two-resistor circuit is ___________ the voltage across the resistor in the one-resistor circuit.

The current through each resistor in the two-resistor circuit is _________ the current through the resistor in the one-resistor circuit (the circuit in Part A). The voltage across each resistor in the two-resistor circuit is ___________ the voltage across the resistor in the one-resistor circuit.

• the same as / half
• half / half
• twice / half
• half / twice
• half / the same as
• twice / twice

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##### The nucleus of 8Be, which consists of 4 protons and 4 neutrons

The nucleus of 8Be, which consists of 4 protons and 4 neutrons, is very unstable and spontaneously breaks into two alpha particles(helium nuclei, each consisting of 2 protons and 2 neutrons).

(a)What is the force between the two alpha particles when they are5.00 X 10-15m apart, and (b) what will be the magnitude of the acceleration of the alpha particles due to this force? Note that the mass of an alpha particle is 4.0026 u.

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##### A 7.80-nC charge is located 1.70 m from a 4.30-nC point charge.

A 7.80-nC charge is located 1.70 m from a 4.30-nC point charge.

(a) Find the magnitude of the electrostatic force that one charge exerts on the other.

(b) Is the force attractive or repulsive?

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##### What is the resistance of a nichrome wire at 0.0 degrees C if its resistance 100.00 ohms at 11.5 degrees C?

a)What is the resistance of a nichrome wire at 0.0 degrees C if its resistance 100.00 ohms at 11.5 degrees C?

(b)What is the resistance of a carbon rod at 25.8 degrees C if its resistance is 0.0160 ohms at 0.0 degrees C?

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