5.1 A car is traveling along a highway at 65 miles per hour. The road is horizontal (0% slope). If the wind resistance and rolling resistance at the wheels creates a combined resistive force of 950 N, what is the power (kW) developed at the rear wheels?

5.2 How much power (kW) must the car engine in problem 5.1 develop if the overall mechanical efficiency of the transmission and drive train is 94%?

5.3 Assume the car engine in problem 5.1 is operated on gasoline with an energy content of 113,500 Btu's per gallon, and that the thermal efficiency of the spark ignition engine and drivetrain is 28.6%. What is the fuel efficiency of the car in miles per gallon?

5.4 The car in problem 5.1 approaches a mountain and begins ascending a grade of 6.0%. If the car maintains an uphill speed of 70 miles per hour, how much additional power (kW) must be developed by the engine to overcome the change in elevation? Assume the car has a mass of 1400 kg.

5.5 Assume the car above is operated on a blend of 85% ethanol and 15% gasoline (E85). If the energy content of ethanol is 80,460 Btu's per gallon, what is the energy content of the E85 fuel (Btu/gal)?

5.6 Assume the overall thermal efficiency of the engine and drivetrain of the car above drops to 24.5% when operated on E85 fuel. What is the estimated fuel economy (km/L) of the car above when subjected to the uphill operating conditions above (Problem 5.4)?

I good now. thanks

The women’s record for fastest serve is by Sabine Lisicki with 131 mph which is approximately 58.56 m/s.  Suppose she hit the ball at a height of 2.6 meters above the court at an angle of 8 degrees below the horizontal.

a.  How high will the ball be when it reaches the net which is 11.89 meters away from the baseline?  Assume she hit the ball right above the baseline.  Does it hit the net or cross over it if the net height is 0.91 meters at the center?

b.  If she served the exact same way, but now with no net in front of her, how far from where she hit the ball would it land on the court?

c.  How fast is the ball going right before it hits the court?  Give the ball’s horizontal, vertical, and resultant velocity.  With the resultant, make sure to give both its size and direction (angle and reference)

A meterstick (L = 1 m) has a mass of m = 0.19 kg. Initially it hangs from two short strings: one at the 25 cm mark and one at the 75 cm mark.

What is the tension in the left string right after the right string is cut?

Explain the relation between the induced electromotive force and the sectional area of the secondary coil, while the number of turns of the secondary coil keeps constant.

A 2.00kg bucket containing 11.5kg of water is hanging from a vertical ideal spring of force constant 140N/m and oscillating up and down with an amplitude of 3.00 cm. Suddenly the bucket springs a leak in the bottom such that water drops out at a steady rate of 2.00 g/s.

Part A

When the bucket is half full, find the period of oscillation.

Part B

When the bucket is half full, find the rate at which the period is changing with respect to time.

Part C

Is the period getting longer or shorter?

Part D

What is the shortest period this system can have?

Squid use jet propulsion for rapid escapes. A squid pulls water into its body and then rapidly ejects the water backward to propel itself forward. A 1.5 kg squid (not including water mass) can accelerate at 20 m/s² by ejecting 0.15 kg of water.

Draw Motion Diagram and Free body Diagram

A recent home energy bill indicates that a household used 475 kWh (kilowatt-hour) of electrical energy and 225 therms for gas heating and cooking in a period of 1 month. Given that 1.00 therm is equal to 29.3 kWh, how many milligrams of mass would need to be converted directly to energy each month to meet the energy needs for the home?(in mg)

A toy cannon uses a spring to project a 5.39-g soft rubber ball. The spring is originally compressed by 5.04 cm and has a force constant of 8.10 N/m. When the cannon is fired, the ball moves 15.6 cm through the horizontal barrel of the cannon, and the barrel exerts a constant friction force of 0.032 5 N on the ball.

(a) With what speed does the projectile leave the barrel of the cannon?
m/s

(b) At what point does the ball have maximum speed?
cm
(from its original position)

(c) What is this maximum speed?
m/s

Absorpstion spectrum of hydrogen shows line in 404.7 nm ; 435.8 nm and 486.3 nm.

Determine:
a. Transtition for each line above
b. Ionization energy of Hydrogen

[Question doesn't state about spectral series (Lyman, Balmer.....). I am confused about this part. How I determine n1?]

A bullet of mass m1 is fired horizontally into a wooden block of mass m2 resting on a horizontal surface. The coefficient of kinetic friction between block and surface is μk. The bullet remains embedded in the block, which is observed to slide a distance s along the surface before stopping.

What was the initial speed of the bullet?

Take the free-fall acceleration to be g.

Q3 Scenario: Discharge the electroscope and charge it again with the rubber rod. Rub the perspex rod with silk and bring it close to the metal disk on top of the electroscope, but do not touch the disk! Go back and forth with the perspex rod several times without touching the metal disk. (Pretend you have a magic wand and you’re casting a spell on the electroscope).

a) What happens when you rub the perspex rod with silk and bring it close to the metal disk on top of the electroscope, but without touching the disk? Explain.

b) When observing the oscillations of the needle, what direction does the electroscope needle go as you bring the rod closer to the metal disk? Explain.

c) What causes the electroscope needle to deflect in that manner? Explain.

d) Does the perspex rod have the same or opposite charge as the needle? Explain.

1. An ideal transformer has a primary with 25 turns and secondary with 15 turns. The load resistor is 24 ? and the source voltage is 85 Vrms.What is the rms electric potential across the 24 ? load resistor?

Answer in units of Vrms

2. A transformer consists of two coils of wire wound on a common toroidal iron core. The mutual inductance of the pair is 483 mH and the current in the first coil decreases from 29 A to 0 in 2.9 s.

What is the induced emf in the second coil? Answer in units of V.

3.If the outer coil has 14.7 turns, a radius of 19 cm and length of 7.47 cm and the inner coil has 628 turns, a radius of 7 cm, and a length of 33.3 cm, find the mutual inductance of the circular coil and solenoid.

Answer in units of ?H

4. Now the current in the solenoid is increased linearly at a rate of di/dt = a =20.2 A/s.

What is the magnitude of the voltage E across the circular coil?

Answer in units of ?V.

A 14.0 m uniform ladder weighing 480 N rests against a frictionless wall. The ladder makes a 63.0°-angle with the horizontal.

(a)

Find the horizontal and vertical forces (in N) the ground exerts on the base of the ladder when an 850-N firefighter has climbed 4.10 m along the ladder from the bottom.

horizontal force

magnitude Ndirection ---Select--- towards the wall away from the wall

vertical force

magnitude Ndirection ---Select--- up down

(b)

If the ladder is just on the verge of slipping when the firefighter is 9.20 m from the bottom, what is the coefficient of static friction between ladder and ground?

(c)

What If? If oil is spilled on the ground, causing the coefficient of static friction to drop to half the value found in part (b), what is the maximum distance (in m) the firefighter can climb along the ladder from the bottom before the ladder slips?

m

An electric motor exerts a constant torque of τ=10N⋅m on a grindstone mounted on its shaft; the moment of inertia of the grindstone is I=2.0kg⋅m2. If the system starts from rest, find the work done by the motor in 8.0 s and the kinetic energy at the end of this time. What was the average power delivered by the motor? Part A:Suppose we now turn off the motor and apply a brake to bring the grindstone from its greatest angular speed of 36 rad/s to a stop. If the brake generates a constant torque of 13 N⋅m , find the total work done (including signs) needed to stop the grindstone. Part A:Suppose we now turn off the motor and apply a brake to bring the grindstone from its greatest angular speed of 36 rad/s to a stop. If the brake generates a constant torque of 13 N⋅m , find the total work done (including signs) needed to stop the grindstone. Part B:Find the average power (including signs) needed to stop the grindstone in Part A.