Presentation on theme: "Lets Practice Drawing FBD’s and Solving Problems"— Presentation transcript:
1 Lets Practice Drawing FBD’s and Solving Problems Contact and Forces at a distance T, N, W, and Friction
2 A net horizontal force of 3000 N is applied to a 1000 kg car A net horizontal force of 3000 N is applied to a 1000 kg car. What will the car's acceleration be after 5 s if it started from rest?
3 A 3 kg particle starts from rest and moves a distance of 4 m in 2 s under the action of a single, constant force. Find the magnitude of the force.
4 LOVE IN AN ELEVATOR…. A 2000 kg elevator has a downward acceleration of 1.0 m/s2. (a) What is the tension in its supporting cable? (b) The same elevator later has an upward acceleration of 1.5 m/s2. What is the tension in its cable now?
5 A 2000 kg elevator is moving upward at a speed of 6 m/s A 2000 kg elevator is moving upward at a speed of 6 m/s. If it takes the elevator 5 s to come to a complete stop, what is the tension in the supporting cable during this slowing down phase.
6 A sphere of mass 2. 50 kg is suspended from a cord A sphere of mass 2.50 kg is suspended from a cord. A steady horizontal breeze pushes the sphere so that the cord makes an angle of 30˚ with the vertical when at rest. Find (a) the magnitude of that push and (b) the tension in the cord.
7 A 5. 0 kg block whose initial speed is 3 A 5.0 kg block whose initial speed is 3.0 m/s slides on a smooth floor for 3.0 m before it comes to a stop. (a) Find the coefficient of kinetic friction. (b) How much force would be needed to keep the block moving at constant speed across the floor?
8 A 20 kg block is initially at rest on a rough, horizontal surface A 20 kg block is initially at rest on a rough, horizontal surface. A horizontal force of 75 N is required to set the block in motion. After it is in motion, a horizontal force of 60 N is required to keep the block moving with constant speed. Find the coefficients of static and kinetic friction from this information?
9 A driver shifts into neutral when her 1200 kg car is moving at 20 m/s and finds that its speed has dropped to 10 m/s 10 s later. What was the average drag force acting on the car?
10 Sled at an angleA horse pulls a 300 kg sled at constant speed over level snow by a rope that is 30˚ above the horizontal. If the coefficient of kinetic friction is 0.20, find the force the rope exerts on the horse.
11 A skier starts from rest and slides 50 m down a slope that makes an angle of 30˚ with the horizontal. She then continues sliding on level snow. (a) If the coefficient of kinetic friction between skis and snow is 0.15 and air resistance is neglected, what is the speed of the skier at the foot of the slope? (b) How far away from the foot of the slope does she come to a stop?
13 Atwood’s MachineMass 1 is larger than Mass 2. Derive the equations for Tension in the string and acceleration.
14 Atwoods MachineIn a horizontal Atwoods machine, a 10 kg mass is attached to a 5 kg hanging mass. For a frictionless surface, (a) what is the acceleration of the system? (b) What is the tension in the string?
15 Horizontal Atwood Machine In a horizontal Atwood machine, a 10 kg mass is attached to a 5 kg hanging mass. If there is a coefficient of friction of 0.2 between the 10 kg mass and the surface, (a) what is the acceleration of the system? (b) What is the tension in the string?