# Two people, A and B, with masses of 50kg and 60kg,

Get college assignment help at uniessay writers Two people, A and B, with masses of 50kg and 60kg, respectively, stand on a frictionless surface 10m apart. B pulls on a connecting rope, giving A an acceleration of 0.92m/s2 towards B. a) what is B’s acceleration toward A?

## An airplane flies due south at 185 km/h relative to the

An airplane flies due south at 185 km/h relative to the air. There is a wind blowing at 83 km/h to the east relative to the ground. What are the plane’s speed and direction relative to the ground?

## At time t=0 the particle has its maximum spreed of 20.0

At time t=0 the particle has its maximum spreed of 20.0 m/s and is ….. at the rate of 115 bullets/min, the speed of each bullet being 400 m/s. Suppose too that the bullets rebound straight back with no change in speed. What is the magnitude of the average force on Superman’s chest from the stream of bullets? …

## A motorcycle has a constant speed of 24.0 m/s as it

A motorcycle has a constant speed of 24.0 m/s as it passes over the top of a hill whose radius of curvature is 131 m. The mass of the motorcycle and driver is 348 kg. (a) Find the magnitude of the centripetal force that acts on the cycle. (b) Find the magnitude of the normal force that acts on the cycle.

## A car is moving down a street at 53 km/h. A

A car is moving down a street at 53 km/h. A child suddenly runs into the street. If it takes the driver 0.74 s to react and apply the brakes, how many meters will the car have moved before it begins to slow down?

## A golf ball of mass 0.045 kg is hit off the

A golf ball of mass 0.045 kg is hit off the tee at a speed of 43 m/s. The golf club was in contact with the ball for 4.7×10-3 s. Find the magnitude of the impulse imparted to the golf ball

## 28-kg girl is bouncing on a trampoline. During a certain interval

28-kg girl is bouncing on a trampoline. During a certain interval after leaving the surface of the trampoline, her kinetic energy decreases to 170 J from 470 J. How high does she rise during this interval? Neglect air resistance

## A 56kg skier starts from rest at the top of a

A 56kg skier starts from rest at the top of a 1200m long trail which drops a total of 230m from top to bottom. At the bottom, the skier is moving 11m/s. How much energy was dissipated by friction?

## The balances read 385 g and 115 g as shown. Both

The balances read 385 g and 115 g as shown. Both are 20 cm from each end of a meterstick. Assume the meterstick has zero mass and use torques to calculate the position of the 500 g weight on the stick.

## Two lifeguards pull on ropes attached to a raft. If they

Two lifeguards pull on ropes attached to a raft. If they pull in the same direction, the raft experiences a net external force of 322 N to the right. If they pull in opposite directions, the raft experiences a net external force of 152 N to the left. Draw a free body diagram for each situation and find the magnitude of the larger of the two individual forces. Answer in units of N.

## At t = 0 a grinding wheel has an angular velocity

Get college assignment help at uniessay writers At t = 0 a grinding wheel has an angular velocity of 21.0 rad/s. It has a constant angular acceleration of 21.0 rad/s^2 until a circuit breaker trips at 2.40 s. From then on it turns through 344 rad as it coasts to a stop at constant acceleration.

## A gun shoots bullets that leave the muzzle with a speed

A gun shoots bullets that leave the muzzle with a speed of 338 m/s. If a bullet is to hit a target 104 m away at the level of the muzzle, the gun must be aimed at a point above the target. How far above the target is this point? (Neglect air resistance.)

## A school yard teeter-totter with a total length of 5.5 and

A school yard teeter-totter with a total length of 5.5 and a mass of 36 is pivoted at its center. A 19 child sits on one end of the teeter-totter.Where should a parent push vertically downward with a force of 250 in order to hold the teeter-totter level?

## an Atwood’s machine consists of blocks of masses m1 = 10.1

an Atwood’s machine consists of blocks of masses m1 = 10.1 kg and m2 = 18.4 kg attached by a cord running over a pulley as in the figure below. The pulley is a solid cylinder with mass M = 8.30 kg and radius r = 0.200 m. The block of mass m2 is allowed to drop, and the cord turns the pulley without slipping.

## As shown in the figure , a string is wrapped several

As shown in the figure , a string is wrapped several times around the rim of a small hoop with radius 8.00×10−2 m and mass 0.190 kg. The free end of the string is pulled upward in just the right way so that the hoop does not move vertically as the string unwinds.

## An electric car is designed to run off a bank of

An electric car is designed to run off a bank of 12.0 V batteries with a total energy storage of 2.00 107 J. (a) If the electric motor draws 5.00 kW, what is the current delivered to the motor? (b) If the electric motor draws 5.00 kW as the car moves at a steady speed of 20.0 m/s, how far will the car travel before it is “out of juice”?

## Batteries are rated in terms of ampere-hours (A · h). For

Batteries are rated in terms of ampere-hours (A · h). For example, a battery that can produce a current of 3.00 A for 5.00 h is rated at 15.00 A · h. (a) What is the total energy stored in a 9.0-V battery rated at 49.0 A · h? (b) At \$0.0590 per kilowatt-hour, what is the value of the electricity produced by this battery? NOTE: Enter your response with hundredths precision.

## 130 kW (1.3 105 W) of power is delivered to the

130 kW (1.3 105 W) of power is delivered to the other side of a city by a pair of power lines between which the voltage is 12000 V. (a) What current flows in the lines? (b) Each of the two lines has a resistance of 5 ohms. What is the voltage change along each line? (Think carefully. This voltage change is along each line, not between the lines.) (c) What power is expended as heat in both lines together (distinct from power delivered to customers)? Do you see why it is so important to step voltages up with transformers for long-distance transmission?

## The process of scattering of light by a molecule (Rayleigh scattering)

The process of scattering of light by a molecule (Rayleigh scattering) is an important physical phenomenon. Instead of thinking of scattering as light simply bouncing off the molecule, one should think of it as an absorption followed by reradiation of light. The probability for light to be scattered is proportional to the inverse of the wavelength to the fourth power, . This means that the shorter wavelengths (toward blue) get scattered more strongly than the longer wavelengths (toward red). Rayleigh scattering can explain why the daytime sky looks blue, the sunset looks red, and clouds are white. In the afternoon you observe mostly scattered light (blue); in the evening you see mostly transmitted light (red). The clouds have higher concentration of water and ice droplets. This means that light gets rescattered many times and all wavelengths get a chance to scatter out of the clouds, adding up to white light. Another effect that can be explained by light scattering is polarization. When you look at the sky with Polaroid sunglasses it appears darker or brighter from different angles. This is because the scattered light is partially polarized. The white light scattered from the clouds is unpolarized, because the light scatters randomly, multiple times. The direction of its polarization becomes random and thus the light is unpolarized. This effect can be useful for making dramatic photographs of the sky. Consider a photographer who wants to take a picture of an interesting cloud formation. To increase the ratio of the clouds’ intensity to that of the blue sky the photographer uses a polarizing filter. Find the angle between the filter’s polarizing axis and the direction of polarization of light necessary to increase the ratio of the clouds’ intensity to that of the blue sky so that it is three times the normal value.

## The cylindrical space station in the figure below, 200 {rm m}

The cylindrical space station in the figure below, 200 {rm m} in diameter, rotates in order to provide artificial gravity of g for the occupants. How much time does the station take to complete one rotation?

## You tie a string to a rock and twirl it at

You tie a string to a rock and twirl it at a constant speed in a horizontal circle with a radius of 1.30 m, 2.10 m above the ground. The rock comes loose and travels as a projectile a horizontal distance of 9.40 m before striking the ground. (a) What was the magnitude of the centripetal acceleration of the rock when it was on the string? (b) What was its speed when it was on the string?

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