Rigid Objects in Equilibrium, Center of Gravity

A lunch tray is being held in one hand. The mass of the tray itself is 0.200 kg, and its center of gravity is located at its geometrical center. On the tray is a 1.00-kg plate of food and a 0.250-kg cup of coffee. Obtain the force T exerted by the thumb and the force F exerted by the four fingers, Both forces act perpendicular t ...continues

Newtons Second Law for Rotational Motion About a Fixed Axis

A ceiling fan is turned on and a net torque of 1.8 N x m is applied to the blades. The blades have a total moment of inertia of 0.22 kg x m^2. What is the angular acceleration of the blades?

Newtons Second Law for Rotation

A CD has a mass of 17 g and a radius of 6.0 cm. When inserted into a player, the CD starts from rest and accelerates to an angular velocity of 21 rad/s in 0.80 s. Assuming the CD is a uniform solid disk, determine the net torque acting on it.

Momentum in 2 dimensions

The picture (attached) shows two pucks about to collide and one of them after the collision, what is the velocity (Magnitude and Direction) of the .4 kg puck after the collision? (The point of the question is to use the conservation of momentum equations) Two blobs of clay have the initial velocities shown below. The velocit ...continues

Relative velocities: airplane, wind and ground.

An airplane flies due west at 185 km/h with respect to the air. There is a wind blowing at 85 km/h to the northeast relative to the ground. What is the plane's speed with respect to the ground? The book's answer is 140 km/h. But it does not show how it arrived at that answer. Do you know?

Components of Vectors

An airplane flies at 65 meters per second in a direction 149 degrees counterclockwise from east. What are the east and north components of the plane's velocity? The book's answer is: -200 m/s for its east velocity and 120 m/s for its north velocity. Can you confirm whether this is correct and show its solution? The book does ...continues

Electrostatic Force

If the electrostatic force between two protons is equal to 1X10^-7 Newtons, what is the distance between them?

Resistor of a wire

What happens to the resistor of a wire if the length of this wire is increased six times and its cross-sectional area is increased two times?

Power

What happens to the power used by an electric appliance if the voltage across this appliance is decreased to half of the origianl value?

Current and voltage

What happens to the current through an electric appliance if the voltage across the appliance is tripled?