12. A simple pendulum is made of a hollow spherical bob full of mercury and suspended by a thin string. If the mercury begins to leak from the small hole at its bottom, then its time period:

(a) Increases.                         (b) Decreases.

(c)First increases and then decreases till it is the same again

(d) First decreases and then increase still it is the same again

The pre-2000’s-style television sets were based on cathode ray tube (CRT) technology. A CRT is a vacuum tube that operates by heating an internal metal filament (the cathode) to a high temperature so that electrons are ejected from its surface. These electrons are then accelerated through a large voltage towards the positively charged anode before striking a phosphor-coated screen to produce visible light. Assume that the electrons start from rest and are accelerated across a voltage difference of 1000~V1000 V. Calculate the speed of the electron when it strikes the phosphor-coated screen.

A block of mass 0.5 kg is pushed against a horizontal spring of negligible mass, compressing the spring a distance of Δx as shown in Figure 5. The spring constant is 450 N/m. When released the block travels along a frictionless horizontal surface to point B, the bottom of a vertical circular track of radius R = 1 m and continues to move up the track. The circular track is not smooth. The speed of the block at the bottom of the vertical circular track is vB = 12 m/s, and the block experiences an average frictional force of 7.0 N while sliding up the curved track.

What was the initial compression of the spring?

What is the speed of the block at the top of the circular track?

Does the block reach the top of the track, or does it fall off before reaching the top?

Suppose two highly precise, identical clocks are synchronized and one clock is placed at the North Pole and one clock is placed at the equator. After 100 years, how much will the clocks differ in time? You can assume Earth is a perfect sphere of radius 6.37 x 10⁶ m and makes one revolution in exactly 24 hours.

(You will have to use a spreadsheet program that holds a lot of decimal places rather than your calculator to find your answer.)

a 2.34-kg cart on a long, level, low friction track is heading for a small electric fan at 0.21 m/s. The fan which was initially off, is turned on. As the fan speeds up, the magnitude of the force it exerts on the cart is given by at^2, where a=0.0200 N/s^2

A. What is the speed of the cart 3.5 s after the fan is turned on? (first i got 0.4958 m/s but was wrong)

B. After how many seconds is the cart's velocity zero

You want to use the idea of electromagnetic induction to make the bulb in your small flashlight glow; it glows when the potential difference across it is 1.5 V. You have a small bar magnet and a coil with 100 turns, each with area 3.0

A solid wood door 1.00 m wide and 2.00 m high is hinged along one side and has a total mass of 45.0kg . Initially open and at rest, the door is struck at its center by a handful of sticky mud with mass 0.400 kg , traveling perpendicular to the door at 12.0 m/s just before impact.

A) Find the final angular speed of the door

B) Does the mud make a significant contribution to the moment of inertia? Yes or no?

In the figure, three 0.03 kg particles have been glued to a rod of length L = 9 cm and negligible mass and can rotate around a perpendicular axis through point O at one end. How much work is required to change the rotational rate (a) from 0 to 20.0 rad/s, (b) from 20.0 rad/s to 40.0 rad/s, and (c) from 40.0 rad/s to 60.0 rad/s? (d) What is the slope of a plot of the assembly's kinetic energy (in joules) versus the square of its rotation rate (in radians-squared per second-squared)?

The active element of a certain laser is made of a glass rod 29.0 cm long and 1.40 cm in diameter. Assume the average coefficient of linear expansion of the glass is equal to 9.00 10-6 (°C)−1. The temperature of the rod increases by 62.0°C.

(a) What is the increase in its length? . cm

(b) What is the increase in its diameter?. cm

(c) What is the increase in its volume? cm3

What is the relationship between the frequency of light and its color?

A defibrillator delivers a jolt of electrical energy to restart a heart that is either stopped or undergoing ventricular defibrillation -- a rapid irregular beating. This energy is supplied by a charged capacitor and applied via paddles placed on a patient's body(one on each side of the heart). Consider a 20.7 μF capacitor charged to 2210 V in a defibrillator and used on a patient. After 9.85×10^-2 seconds the voltage across the defibrillator's paddles drops to 49.6 V.

Find the effective resistance of the body between the defibrillators paddles. Hint: assume the voltage across the paddles is the same as the voltage stored on the capacitor.

A baseball pitcher throws a pitch horizontally from a height of 6 feet with an initial speed of 130 feet per second. a) find a vector valued function describing the position of the ball t seconds after release. b) if home plate is 60 feet away, how high is the ball when it crosses home plate? c)if a person drops a ball from height of 6 feet at the same time the pitcher releases the ball, how high will the dropped ball be when the pitch crosses home plate?

A demented scientist creates a new temperature scale, the "Z scale." He decides to call the boiling point of nitrogen 0 ?Z and the melting point of iron 1000 ?Z.

Part A

What is the boiling point of water on the Z scale?

T_Z = 171 Z

Part B

Convert 1000 ?Z to the Celsius scale.

Part C

Convert 1000 ?Z to the Kelvin scale.

i). How far a driver travel in 80 min. along a straight road if his average velocity is 90 Km/h.

II). If the position of moving an object is given by ?(?) = ??? − ??

a) Calculate the displacement of the particle during the interval t=3s to t=5s.

b) Determine the instantaneous velocity of the particle at t=8s c) Determine the instantaneous acceleration of the particle at t=6s.

IP A charging bull elephant with a mass of 5100 kg comes directly toward you with a speed of 4.50 m/s . You toss a 0.200-kg rubber ball at the elephant with a speed of 7.60 m/s .

What is the speed when it bounces back at you