For the device shown with a bar of length, L, and mass, m, of negligible resistance moving with an initial speed, vbar, across a region of space with a constant magnetic field directed out of the page. A resistor, R, is connected across the two conducting rails with negligible resistance. Which expression gives the best description of the distance, x, traveled by the bar before it stops?
A heavy stone block, having mass M, is moved laterally (from rest) on two identical cylindrical rollers, radius R and mass m, by a constant force F. The friction at the ground is sufficient to cause the rollers to roll without sliding. Develop an expression for the speed of the block after it moves a distance din terms of F, d, M and m. Use the principle of work and energy and, box your answer, and show your work.
A projectile is shot directly away from Earth's surface. Neglect the rotation of the Earth. What multiple of Earth's radius RE gives the radial distance (from the Earth's center) the projectile reaches if (a) its initial speed is 0.749 of the escape speed from Earth and (b) its initial kinetic energy is 0.749 of the kinetic energy required to escape Earth? (Give your answers as unitless numbers.) (c) What is the least initial mechanical energy required at launch if the projectile is to escape Earth? (a) Number Units (b) Number Units (c) Number Units
The figure shows wire section 1 of diameter D1 = 5.00R and wire section 2 of diameter D2 = 4.00R, connected by a tapered section. The wire is copper and carries a current. Assume that the current is uniformly distributed across any cross-sectional area through the wire's width. The electric potential change V along the length L = 2.10 m shown in section 2 is 13.0 μV. The number of charge carriers per unit volume is 8.70×1028 m−3. What is the drift speed of the conduction electrons in section 1? Number Units
In the figure R1 = 10.6 kΩ, R2 = 14.2 kΩ, C = 0.400 μF, and the ideal battery has emf E = 15.0 V. First, the switch is closed a long time so that the steady state is reached. Then the switch is opened at time t = 0. What is the current in resistor 2 at t = 3.60 ms? Number Units
A parallel-plate capacitor has circular plates of 6.15 cm radius and 1.73 mm separation. (a) Calculate the capacitance. (b) What charge will appear on the plates if a potential difference of 144 V is applied? (a) Number Units (b) Number Units
The figure shows wire section 1 of diameter D1 = 5.50R and wire section 2 of diameter D2 = 4.00R, connected by a tapered section. The wire is copper and carries a current. Assume that the current is uniformly distributed across any cross-sectional area through the wire's width. The electric potential change V along the length L = 1.70 m shown in section 2 is 15.0 μV. The number of charge carriers per unit volume is 8.70×1028 m−3. What is the drift speed of the conduction electrons in section 1? Number Units
A metal sphere of radius 19 cm has a net charge of 4.0×10−8 C. (a) What is the electric field at the sphere's surface? (b) If V = 0 at infinity, what is the electric potential at the sphere's surface? (c) At what distance from the sphere's surface has the electric potential decreased by 300 V? (a) Number Units (b) Number Units (c) Number Units
A 0.220 kg block of a pure material is heated from 20.0∘C to 41.5∘C by the addition of 4.25 kJ of energy. Calculate its specific heat (in J/(kg⋅∘C)). J/(kg⋅∘C) Identify the substance of which it is most likely composed. glass asbestos copper aluminum silver
A loaded penguin sled weighing 79.0 N rests on a plane inclined at angle θ = 23.0∘ to the horizontal (see the figure). Between the sled and the plane, the coefficient of static friction is 0.250, and the coefficient of kinetic friction is 0.130. (a) What is the minimum magnitude of the force F→, parallel to the plane, that will prevent the sled from slipping down the plane? (b) What is the minimum magnitude F that will start the sled moving up the plane? (c) What value of F is required to move the sled up the plane at constant velocity?