Harry

The fan blades on a jet engine make one thousand revolutions in a time of 50.2 ms. What is the angular frequency of the blades?

A spring (k = 900 N/m) is hanging from the ceiling of an elevator, and a 6.5-kg object is attached to the lower end. By how much does the spring stretch (relative to its unstrained length) when the elevator is accelerating upward at a = 0.68 m/s2?

The drawing shows three identical springs hanging from the ceiling. Nothing is attached to the first spring, whereas a 4.2-N block hangs from the second spring. A block of unknown weight hangs from the third spring. From the drawing, determine (a) the spring constant (in N/m) and (b) the weight of the block hanging from the third spring.

the second spring hangs down to 35 cm

the third spring hangs down to 50 cm

In a vacuum, two particles have charges of q1 and q2, where q1 = +5.1C. They are separated by a distance of 0.38 m, and particle 1 experiences an attractive force of 4.7 N. What is the value of q2, with its sign?

A blow-dryer and a vacuum cleaner each operate with a voltage of 120 V. The current rating of the blow-dryer is 13 A, while that of the vacuum cleaner is 4.2 A. Determine the power consumed by (a) the blow-dryer and (b) the vacuum cleaner. (c) Determine the ratio of the energy used by the blow-dryer in 11 minutes to the energy used by the vacuum cleaner in 40 minutes.

A blow-dryer and a vacuum cleaner each operate with a voltage of 120 V. The current rating of the blow-dryer is 13 A, while that of the vacuum cleaner is 4.2 A. Determine the power consumed by (a) the blow-dryer and (b) the vacuum cleaner. (c) Determine the ratio of the energy used by the blow-dryer in 11 minutes to the energy used by the vacuum cleaner in 40 minutes.

Two wires are identical, except that one is aluminum and one is copper. The aluminum wire has a resistance of 0.204Ω. What is the resistance of the copper wire? Take the resistivity of copper to be 1.72 x 10-8 Ω·m, and that of aluminum to be 2.82 x 10-8 Ω·m.

Suppose that the resistance between the walls of a biological cell is 3.8 × 109 Ω. (a) What is the current when the potential difference between the walls is 74 mV? (b) If the current is composed of Na+ ions (q = +e), how many such ions flow in 0.72 s?

A defibrillator is used during a heart attack to restore the heart to its normal beating pattern. A defibrillator passes 18 A of current through the torso of a person in 1.7 ms. (a) How much charge moves during this time? (b) How many electrons pass through the wires connected to the patient?

A dentist causes the bit of a high-speed drill to accelerate from an angular speed of 1.39 x 104 rad/s to an angular speed of 3.21 x 104 rad/s. In the process, the bit turns through 1.73 x 104 rad. Assuming a constant angular acceleration, how long would it take the bit to reach its maximum speed of 7.79 x 104 rad/s, starting from rest?

The drawing shows the top view of two doors. The doors are uniform and identical. Door A rotates about an axis through its left edge, and door B rotates about an axis through its center. The same force is applied perpendicular to each door at its right edge, and the force remains perpendicular as the door turns. No other force affects the rotation of either door. Starting from rest, door A rotates through a certain angle in 2.00 s. How long does it take door B (also starting from rest) to rotate through the same angle?

The wheel of a car has a radius of 0.310 m. The engine of the car applies a torque of 311 N·m to this wheel, which does not slip against the road surface. Since the wheel does not slip, the road must be applying a force of static friction to the wheel that produces a countertorque. Moreover, the car has a constant velocity, so this countertorque balances the applied torque. What is the magnitude of the static frictional force?

One end of a meter stick is pinned to a table, so the stick can rotate freely in a plane parallel to the tabletop. Two forces, both parallel to the tabletop, are applied to the stick in such a way that the net torque is zero. The first force has a magnitude of 2.00 N and is applied perpendicular to the length of the stick at the free end. The second force has a magnitude of 6.00 N and acts at a 55.8o angle with respect to the length of the stick. Where along the stick is the 6.00-N force applied? Express this distance with respect to the end of the stick that is pinned.