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Mechanics: Seven multiple choice questions

1. What is the tangential speed of Nairobi, Kenya, a city near the equator? The earth makes one revolution every 23.93 h and has an equatorial radius of 6380 km. A) 74.0 m/s B) 116 m/s C) 148 m/s D) 232 m/s E) 465 m/s 2. The radius of the earth is 6.38 x 106 m and its mass is 5.98 x 1024 kg. What is the accelerat

Mass and Spring Oscillations

A mass is oscillating on a spring with a period of 4.60 s. At t=0 s the mass has zero speed and is at x=8.30cm. What is its acceleration at t=2.50s?

Newton's Laws of motion: Block over block problem

A block of mass m1 = 4.70 kg sits on top of a second block of mass m2 = 16.3 kg, which in turn is on a horizontal table. The coefficients of friction between the two blocks are µs = 0.300 and µk = 0.100. The coefficients of friction between the lower block and the rough table are µs = 0.600 and µk = 0.500. You apply a consta

Classical Mechanics: Momentum and Velocity

A 4.0 kg toy race car can move along an x axis. The figure below gives Fx of the force acting on the car, which begins at rest at time t = 0. (The vertical axis is marked in increments of 2 N.) See the attached document for the necessary graph. (a) What is the momentum of the car at t = 6.0 s (b) What is the moment

Work and Average Acceleration

Zak, helping his mother rearrange the furniture in their living room, moves a 50-kg sofa 6 meters with a constant force of 20 newtons. Neglecting friction, a. What is the work done by Zak on the sofa? b. What is the average acceleration of the sofa?

Determining Acceleration of a Block: Example Problem

A 42.0 Kg block of ice slides down a plane with an incline of 34 degrees. Assuming friction is negligible, what is the acceleration of the block down the incline? 1. 9.80 m/s^2 2. 6.61 m/s^2 3. 8.12 m/s^2 4. 5.48 m/s?

Friction: Acceleration of Two Blocks on an Incline

Two blocks, of weights 3.6 N and 7.2 N, are connected by a mass-less string and slide down a 30 degree inclined plane. The coefficient of kinetic friction between the 3.6 N block and the plane is 0.10, while there is no friction between the 7.2 N block and the plane. Determine: a) the acceleration of each of the blocks b) th

Physics - Classical Mechanics - Rotational Motion

An astronaut is being tested in a centrifuge. The centrifuge has a radius of 10 m and, in starting, rotates according to theta = (0.30 rad/s?t? where t is in seconds and theta is in radians. When t = 5.0 s, what are the magnitudes of the astronaut's (a) rotational velocity, (b) translational velocity, (c) tangential accele

Moving velocity and mechanics

An airplane was moving with a velocity equal to 300 mph when the velocity was increased with uniform acceleration to 600 mph in 15 min, calculate the number of miles the airplane traveled during that interval of time

Simple Harmonic Motion: Frequency for vertical Oscillations

A hanging wire has a length of 1.90m. When a steel ball of mass 50.0kg is suspended from the wire, the wire stretches by 2.30mm . If the ball is pulled down a small additional distance and released, at what frequency will it vibrate? Assume that the stress on the wire is less than the proportional limit. Take the free fal

Gravitational Force and Acceleration

Concept Question: A large rock and a small pebble are held at the same height above the ground. (a) Is the gravitational force exerted on the rock greater than, less than or equal to that exerted on the pebble? Justify your answer. (b) When the rock and the pebble are released, is the downward acceleration of the rock gre

Friction: Box in a Truck

Consider a box in back of a pickup truck. 1. If the truck accelerates slowly, the box moves with the truck without slipping. What force or forces act on the box to accelerate it? In what direction do these forces point? 2. Draw a free body diagram of the box 3. What happens to the box if the truck accelerates too rapi

Discuss the Problem-Solving Process outlined. Which step is the most important? Could students solve problems without one of these steps? Give an example of a problem and demonstrate its solution through the four steps. Four-Step Problem-Solving Process 1. Understanding the problem a. Can you state the problem in your own words? b. What are you trying to find or do? c. What are the unknowns? d. What information do you obtain from the problem? e. What information, if any, is missing or not needed? 2. Devising a plan The following list of strategies, although not exhaustive, is very useful: a. Look for a pattern. b. Examine related problems and determine if the same technique applied to them can be applied to the current problem. c. Examine a simpler or special case of the problem to gain insight into the solution of the original problem. d. Make a table or list. e. Make a diagram. f. Write an equation. g. Use guess and check. h. Work backward. i. Identify a subgoal. j. Use indirect reasoning. k. Use direct reasoning. 3. Carrying out the plan a. Implement the strategy or strategies in step 2 and perform any necessary actions or computations. b. Check each step of the plan as you proceed.This may be intuitive checking or a formal proof of each step. c. Keep an accurate record of your work. 4. Looking back a. Check the results in the original problem. (In some cases, this will require a proof.) b. Interpret the solution in terms of the original problem. Does your answer make sense? Is it reasonable? Does it answer the question that was asked? c. Determine whether there is another method of finding the solution. d. If possible, determine other related or more general problems for which the techniques will work.

Discuss the Problem-Solving Process outlined. Which step is the most important? Could students solve problems without one of these steps? Give an example of a problem and demonstrate its solution through the four steps. Four-Step Problem-Solving Process 1. Understanding the problem a. Can you state the problem in your ow

Projectile Motion: Minimum Speed of to Cross a Log

Please help - hope you can explain me the steps also: A cylindrical tree trunk with a circular cross-section has a diameter of 20 cm. The trunk rests horizontally on the flat ground. A grasshopper jumps from the ground on one side of the tree trunk to the ground on the other side without touching the tree trunk. What is the m

Bungee jumping: Kinematics, energy and period of oscillations

Your adventurous friend Lola goes bungee jumping. She leaps from a bridge that is 100 m above a river. Her bungee cord has an unstretched length of 55 m and a spring constant k=750 N/m. Lola has a mass of 45kg 1. How fast is she falling when she just starts to stretch the cord? How long does it take for Lola to reach this poi

Circular motion of conical pendulum

Consider a conical pendulum with a 80.0 kg bob on a 10.0 m wire making an angle of θ = 5.00° with the vertical. (Consider + to be towards the center of the circular path.) (a) Determine the horizontal and vertical components of the force exerted by the wire on the pendulum. _____N +_____N (b) What is the radial

Four problems on dynamics.

Please see attachment for fig. 24. Pictures below (see attachment) show the loads hanging from the ceiling of an elevator that is moving at constant velocity. Find the tension in each of three strands of cord supporting each load. 26. Angle phi =15 degree. Assuming the block start from the rest at the top and that the leg

Newton's Law of Motion: Contact Force and Acceleration

Two crates, of mass 75 kg and 107 kg, are in contact and at rest on a horizontal surface. A 732 N force is exerted on the 75 kg crate. If the coefficient of kinetic friction is 0.15, calculate the following: (a) the acceleration of the system in m/s/s. (b) the force that each crate exerts on the other in N.

Acceleration of the elevator and tension of the rope

How much tension must a rope withstand if it it used to accelerate a 1700 kg car vertically upward at 0.4 m/(s ^2)? A person stands on a bathroom scale in a motionless elevator. When the elevator begins to move, the scale briefly reads only 0.65 of the person's regular weight. What are the direction and magnitude of the acc

block sliding down a frictionless incline

Please see the attached file. A block of mass m = 2.00 kg is released from rest at h = 0.400 m from the surface of a table, at the top of a theta = 40.0 degrees incline as shown below. The frictionless incline is fixed on a table of height H = 2.00 m. (a) Determine the acceleration of the block as it slides down the incli

Rotational Dynamics: Acceleration of Mass

1. What is the acceleration of a system consisting of two masses, of 200 grans and 215 grams, respectively, tied at the end of a light cord passing over a frictionless pulley of 150 grams mass and 4 cm. radius, if the masses start at the same level from rest? 2. A string is wound on the edge of a disk weighing 2.5 kg and havi

Average Acceleration of Nitrogen Molecule in Air

The average speed of a nitrogen molecule in air is about (6.70 x 10^2) m/s, and its mass is about (4.68 x 10^-26) kg. (a) If it takes (3.00 x 10^-13) seconds for a nitrogen molecule to hit a wall and rebound with the same speed but moving in an opposite direction (assumed to be the negative direction), what is the average acc

Newton's Laws of Motion: Acceleration, Pulley and Incline

The following equations describe the motion of a system of two objects: +n - (5.00 kg)(9.8 m/s2)cos 15.0° = 0 fk = 0.360n +T + (5.00 kg)(9.8 m/s2)sin 15.0° - fk = (5.00 kg)a -T + (3.10 kg)(9.8 m/s2) = (3.10 kg)a (a) Solve the equations for a and T. a (in m/s2)= T (in N)= In what situation might these equations be u

Simple harmonic motion

Please see the attached file. A piston executes simple harmonic motion with amplitude of 0.1 m. If it passes through the center of its motion with a speed of 0.5 m/s, what are the maximum accelerations and the period of oscillation?

System of three particles

Consider a system of three particles, each of mass m, whose motions are described by {m_1a_1 = F_12 + F_13, m_2a_2 = F_21 + F_23, m_3a_3 = F_31 + F_32}. If particles 2 and 3, even though not rigidly bound together, are regarded as forming a composite body of mass 2m located at their mid-point r = (1/2)*(r_2 + r_3), find the

Block on an Inclined Plane

Please see attached file for full problem statement. 4. A block of mass M has a string of mass m attached to it. A force F is applied to the string and it pulls the block up a frictionless plane that is inclined at an angle theta to the horizontal. Find the force that the string exerts on the block.

Physics - Force & Motion

1. A 3200-lb elevator cab is supported by a cable in which the maximum safe tension is 4000 lb. (a) What is the greatest upward acceleration the elevator cab can have? (b) The greatest downward acceleration? 2. A box is sliding down a frictionless plane inclined at an angle of 30° with the horizontal. What is the acc

Force and Motion

1.(a) What is the weight of an object whose mass is 50 slugs? (b) What is the mass of an object whose weight is 50lb? 2. How much force is needed to bring a 3200-lb car from rest to a velocity of 44 ft/s in 8 seconds?