Projectile motion-initial speed

A soccer player kicks a rock horizontally off a 40.0m high cliff into a pool of water. If the player hears the sound of the splash 3.00s later, what was the initial speed given to the rock? Assume the speed of sound in air to be 343m/s

Projectile motion

A projectile is fired in such a way that its horizontal range is equal to three times its maximum height. What is the angle of projection?

A rod & mass system, is released to rotate in a vertical circle. Find the tensions in the rod at the the lowest point.

A rigid rod with negligible mass has a length L= 2.6 m. The rod can rotate freely about a fixed pivot at one end. Attached at the other end of the rod is mass M1 = 8.4 kg, and at its center is mass M2 = 3.6 kg. The system is released from vertical at rest to rotate about the pivot. SEE ATTACHMENT #1 for a diagram showing parameters. PART a. Find the velocity V1 of the end mass, and the velocity V2 of the mass at the center as the rod passes through vertical after half a rotation. PART b. Find the tension T1 in the rod between the masses, and also the tension T2 in the rod betwen pivot and the center mass.

A rock, mass unknown, slides down a hill. Find average friction force and mass.

A rock starts from rest then slides distance L= 5 m down a concave hill to a point which is h= 3 m below starting point. SEE ATTACHMENT #1 for a diagram showing parameters. During the slide, Q= 111 joules of heat are generated, and the final speed is V= 4.8 m/sec. PART a. Find the average friction force. PART b. Find the mass of the rock.

Center of mass problem

A uniform bar 2m long and of mass 1 kg is resting on a knife edge placed 40 cm from one end. What mass suspended from that end will keep the bar horizontal.