In this problem
we will examine a system undergoing projectile motion using conservation of energy. Note that you must separate the kinetic energy into its x and y-components, thus the kinetic energy at any position is . The block with mass M = 6 kg is initially at rest against a spring with spring constant k = 60000 N/m. The spring is initially compressed by 0.3 m. There is no friction or air resistance and the heights at each position are shown.
5.Just before it reaches the ground (height = 0 m) what is the kinetic energy of the block? What is the final x-velocity and y-velocity of the block?
An Atwood machine consists of two masses connected by a string using three pulleys as shown. Mass M1 is 5 kg and mass M2 is 12 kg. Pulley 1 has a mass of 2 kg and a radius of 0.05 m. Pulley 2 has a mass of 3 kg and a radius of 0.08 m. Pulley 3 has a mass of 2 kg and a radius of 0.09 m. The Moment of Inertia of a pulley is .
A small projectile with mass m = 0.005 kg is moving toward a large block with mass M = 1.100 kg. The large mass is attached to a spring with spring constant k = 15 N/m. It rests on a surface with a coefficient of kinetic friction μk = 0.25. The small projectile is initially traveling at v = 13 m/s.
The two masses collide in a perfectly INELASTIC collision and together they are pushed to the right by a distance Xf before coming to rest.
A commonly held myth is that if you were trapped in a falling elevator and you jump upward just before the elevator crashes you can escape injury. We will assume the maximum velocity a human can attain while jumping is 3 m/s upward.
Just before the elevator crashes it is traveling at 20 m/s downward. The human has a mass of 60 kg and the elevator has a mass of 1500 kg. The collision occurs over a 0.4 second interval. After the collision, the elevator and human are both at rest.
1.Relevant concepts/equations.
A rod with length L = 2.2 m rests on a frictionless surface. The rod has mass of M = 0.1 kg. A small projectile with mass m = 0.02 kg is traveling toward the rod at a velocity of 12 m/s. The particle strikes the rod at one end and sticks to the rod. See illustration.
1.Relevant concepts/equations.
2.The projectile may be treated as a point particle. What is the moment of inertia of the projectile? For a rod rotating about one end the moment of inertia is . What is the moment of inertia of the rod?
3.Just before the projectile strikes the rod what is the projectiles kinetic energy in terms of m and v? What is the angular velocity of the particle?
4.Just before the projectile strikes the rod what is the angular momentum of the particle? What is the angular momentum of the rod?
5.After the particle strikes the rod what is the angular velocity of the mass/rod system? How long does it take the rod to make one complete revolution?
6.If the particle had instead hit the rod at the point (3/4)L from the axis of rotation, would the angular velocity of the mass/rod system be greater or less than the value you found in part 5?