Gravity
An 85 kg person stands on a scale in an elevator accelerating downwards at 2.5 m/s2. Is the person's apparent weight higher or lower?
Name all the forces that have appeared in Free Body Diagrams in this class.
Gravity, normal force, tension, friction, applied force.
You are trying to push a box across the floor but it remains unmoving. What type of friction is acting on the box?
Static friction
If two people pull on opposite ends of a rope with equal force, what is the net force on the rope?
0 N
What is the net force on a 2 kg object accelerating at 3 m/s²?
F=ma=2×3=6N
A 65 kg person is standing on a scale in an elevator accelerating upwards at 2.5 m/s2. What is the net force acting on the person? (include magnitude and direction)
162.5 N (upwards)
Draw a free body diagram of a person standing on a scale in an elevator. The elevator is accelerating downwards. Draw the force vectors proportional to the magnitude of the force.
A 5 kg block is on a horizontal surface with μ = 0.2. What is the force of friction?
9.8 N
A 10 kg mass hangs from a rope. What is the tension in the rope?
98 N
A 20 kg mass is attached to a 10 kg mass with a rope. The 10 kg block is being pulled along at an acceleration of 2.0 m/s2. What is the tension in the rope attaching the two blocks?
40 N
A 50 kg dog is standing in an elevator that is accelerating 3 m/s2 downwards. What is the apparent weight of the dog?
340 N
Draw a free body diagram of a motionless box sitting on an inclined plane. Draw the force vectors proportional to the magnitude of the force.
A 0.5 kg ball is falling towards the Earth at an acceleration of -8.0 m/s2. What is the force of friction (air resistance) acting on the ball?
0.9 N
A 200 kg truck is hauling a 500 kg trailer. The truck is hauling with a force of 800 N. What is the acceleration of the trailer?
1.14 m/s2
A student pulls a sled at an angle of 30° with a force of 50 N. The sled’s mass is 20 kg. What is the horizontal acceleration if friction is negligible?
43.3N
A 2.0 kg mass is sitting on a scale in an elevator. If the scale reads 25N, what is the acceleration of the elevator? (include magnitude and direction)
2.7 m/s2 (upwards)
Draw a free body diagram of a box being pushed up an inclined plane with friction. Draw the force vectors proportional to the magnitude of the force.
You push a 10 kg toolbox across the floor with a force of 39 N and you notice that the box moves at a constant speed. What is the coefficient of friction between the floor and the toolbox?
0.38
Two masses (5 kg and 3 kg) are connected by a string over a frictionless pulley. What is the acceleration of the system?
2.45m/s2
A 19 kg mass and a 13 kg mass are hanging on opposite sides of a frictionless pulley. What is the acceleration of the blocks as they fall?
1.84 m/s2