Friction Addiction
What is friction?
Friction is a force that opposes the motion of objects in contact.
What is the shape of the trajectory of a projectile?
What is the formula for average speed?
Average speed = (total distance) / (total time)
Which type of friction is usually greater: static or kinetic?
Static friction
What is the horizontal acceleration of a projectile if it has an initial velocity of 15 m/s at an angle of 25 degrees (ignoring air resistance)?
0 m/s2
How is velocity different from speed?
Velocity includes direction, while speed does not.
A 10 kg object is pushed with a force of 50 N but doesn’t move. What does this tell you about the static friction?
The static friction force is greater than or equal to 50 N.
A ball is thrown horizontally at 10 m/s from a height of 5 m. How long does it take to hit the ground?
t = 1.01 sec
A car accelerates from 0 to 30 m/s in 5 seconds. What is its acceleration?
a = 6 m/s2
Calculate the force of kinetic friction acting on a 15 kg block sliding on a flat surface with μk=0.2
29.4 N
Calculate the range of a projectile launched at 20 m/s at a 30° angle.
dx =35.35 m
A vector has a magnitude of 10 m and an angle of 60° from the x-axis. What are its components?
Rx = 5 m; Ry = 8.66 m
A 10 kg box is on a 30° incline. The coefficient of static friction is 0.4. Will the box slide? Explain.
Yes. fs = 33.95 N, and fg,x = 49 N.
A ball is launched with a velocity of 25 m/s at an angle of 45°. What is the maximum height it reaches?
h = 15.94 m
*I re-checked my answer, this IS the correct answer8
Two objects are dropped from the same height at the same time. One is dropped straight down, and the other is thrown horizontally. Which one hits the ground first? Why?
They hit the ground at the same time because vertical motion is independent of horizontal motion.