FBD's
A 5.0 kg box rests motionless on a horizontal table.
Draw the free-body diagram for the box.
How many forces act on the box?
Weight - down
Normal - Up
A 10.0 kg box is pulled horizontally across a floor with a 50 N force. The coefficient of kinetic friction is 0.20.
Question: What is the acceleration?
3.04 m/s2
A 4.00 kg bowling ball is moving at 6.00 m/s.
Question: What is its kinetic energy?
72.0J
What is the equation for linear momentum, and what two quantities determine an object's momentum?
Is it a scalar or a vector?
Momentum depends on mass and velocity. Velocity gives momentum its direction.
What is the fastest speed possible in the universe?
The speed of light in a vacuum, approximately 3.00×10^8 m/s
A 10 kg box is pulled to the right across a horizontal surface by a rope. The box is moving, and kinetic friction acts against its motion.
Draw the free-body diagram for the box.
Identify and label every force acting on it.
Fk-- l /
mg
A 5.0 kg block slides down a 30° frictionless ramp.
Question: What is the acceleration?
a= 4.90 m/s^2
A student pushes a 20.0 kg box with a constant horizontal force of 80.0 N over a distance of 5.00 m.
Question: How much work does the student do on the box?
400 J
What is the key difference between an elastic collision and an inelastic collision?
If you are standing on a scale inside an elevator and the elevator suddenly accelerates upward, does the scale reading increase, decrease, or stay the same?
Increase. The upward acceleration requires a larger normal force.
A block rests on a frictionless 30° inclined plane.
Resolve the weight into components parallel and perpendicular to the ramp.
wx= mgsin (30)
wy= mgcos (30)
A 20 kg crate sits on a horizontal floor. The coefficient of static friction is 0.40, and the coefficient of kinetic friction is 0.25.
Questions:
max static = 78.4
F min = 78.4
A 500 kg roller coaster car starts from rest at the top of a frictionless track 25.0 m above the ground.
Question: What is the car's speed when it reaches a point 5.00 m above the ground?
19.8 m/s
A 1,500 kg cybertruck traveling east at 20.0 m/s crashes into a 1,000 kg schoollbus traveling west at 10.0 m/s. The cars stick together. What is their velocity immediately after the collision?
vf= 8.00m/s east (cyber truck wins)
What would happen to your mass if you traveled from Earth to the Moon?
Answer: Nothing — your mass stays the same. Your weight would decrease because the Moon's gravitational field is weaker.
A 20 kg crate is pulled across a horizontal floor by a rope that makes a 35° angle above the horizontal. The crate is moving to the right, and kinetic friction acts against the motion.
Draw the free-body diagram.
Which direction does the normal force point, and is it equal to mg? Explain.
N= mg- T sin 35
A 4.0 kg block sits on a horizontal surface with μk=0.20. It is connected by a rope over a frictionless pulley to a 6.0 kg hanging mass
a= 5.10 m/s^2
T= 28.6 N
A 2.00 kg block is pushed against a spring with k=800 N/m. The spring is compressed 0.300 m and released from rest on a frictionless surface.
Question: What is the speed of the block when the spring returns to its natural length?
v= 6.00m/s
A 60.0 kg person standing on a frictionless surface throws a 5.00 kg ball forward at 12.0 m/s. If the person and ball were initially at rest, what is the person's velocity immediately after throwing the ball?
1.00 m/s backward
If you traveled at the speed of light, how long would it take to travel from Earth to the Moon?
Closest Answer wins
Answer: About 1.3 seconds
A 6.0 kg block sits on a rough 25° incline. A rope attached to the block pulls up the incline at a 20° angle above the surface of the ramp. The block is moving up the ramp, so friction opposes its motion.
I'll draw it
A 12.0 kg block sits on a horizontal surface with coefficients of friction
μs=0.50,μk=0.30 It is connected by a rope over a frictionless pulley to a 5.00 kg hanging mass. 1.Will the system start moving?2. If it moves, what is the acceleration?
The system does not move
Acceleration = 0
A 75.0 kg student runs up a staircase that rises 8.00 m vertically in 6.00 s.
Question: What average power does the student produce, both in watts and horsepower?
1hp= 746 Watt
P=980 Watt, 1.31 hp
A 2.00 kg cart moving at 6.00 m/s to the right collides elastically with a stationary 4.00 kg cart. After the collision, the 2.00 kg cart moves at 2.00 m/s to the left.
What is the velocity of the 4.00 kg cart after the collision?
4.00 m/s to the right
A person jumps off a moving boat onto a dock. The boat moves backward as they jump. What fundamental physics law explains why the boat moves backward?
Conservation of momentum.