Dynamics
What is Newtons first law of motion?
An object at rest stays at rest, or if in motion remains in motion at a constant velocity unless acted on by an external force
What is the difference between scalar and vector quantities?
Scalars only have magnitude
Vectors have magnitude and direction
A car turns a circular curve with a speed of 50 m/s. If the radius of the curve is 100m. What is the centripetal acceleration of the car?
Fc = 25 m/s2
Jay holds a binder at a constant height above the ground. Is he doing work on the binder?
No, the binder must move in order to do work.
John is waiting to cross the road in bali and a firetruck passes through the intersection at a velocity of 20m/s. Its sirens produce a constant frequency of 795 Hz when stationary. The speed of sound is 345m/s.
Determine the frequency dave hears as the firetruck approaches.
John hears a frequency of 845 Hz.
What is Newton's third law of motion?
Every action or force has an equal and opposite reaction.
Mr. Seitz rides his bike at a constant velocity 40m north for 9.8s. Then travels 60m south for 15.1 seconds. What is his average speed and average velocity?
Average speed = 4.0 m/s
Average velocity = 0.80 m/s South
A student whirls a 8.42 g rubber stopper on a 90 cm long string in a horizontal circle at a rate of 2.1 Hz. Calculate the magnitude of the centripetal force acting on the stopper.
The centripetal force is 1.32 N
Jake and Paul pull a 17 kg box. Jake pulls with a force of 62 N to the north. Paul pulls with a force of 50 N south. The box moves a distance of 50 cm. Calculate the net work done on the box.
The net work is 6 joules
Bob has a mass of 58.5 kg. He weights 543 N in an airplane. Determine the acceleration due to gravity at his location.
The acceleration due to gravity at Bob’s location is 9.28 m/s².
A basketball is dropped at a velocity of 6.1 m/s. When the ball springs upwards it has a velocity of 5.4 m/s. The basketball was only in contact with the floor 0.3s. What is the balls acceleration after hitting the floor?
38 m/s2
A 300g ball is dropped from a height of 2.45 m. Determine the balls kinetic energy as it comes in contact with the ground traveling at its maximum velocity.
Ek is 7.21 J.
A hockey puck has a mass of 160 g and is pushed North along the ice at 3 m/s. After traveling 8m the puck comes to rest. Determine the force of friction.
The force of friction is 0.09 N
A rock is thrown 15m/s off the edge of a cliff. It hits the ground 35m from the base of the cliff. What is the height of the cliff?
26.6 meters
Determine the potential energy stored in a spring having a constant of 50 N/m when it is compressed 8.0 cm.
The potential energy of the compressed spring is 0.16 J
Two masses are attached by a light string looped over 2 frictionless pulleys. Object 1 has a mass of 200g and accelerates upward at a rate of 4.9 m/s2. Determine the mass of object 2.
Object 2 has a mass of 600g
A 10kg box is placed on an inclined plane that has an angle of 30 degrees relative to the horizontal. Determine the the static coefficient of friction necessary to keep it stationary.
0.58
Determine the amount of work done in 30s by motor that has a power output of 7.5 kW.
225,000J or 225kJ