Concepts
What are the units for the coefficient of fricition
NO UNITS
A 1200 kg car is driving on a flat road. What is it's acceleration if static friction is pushing it forward with 100 N and drag is 400N?
0.5 m/s^2
You are going to push a chair of mass 5 kg across the floor. The coefficient of static friction between the chair legs and the floor is 0.3. How much force will you have to push with you have to get it moving (meaning the acceleration is 0)?
14.7 N
A rocket takes off from earth going straight up with a force of thrust=3.3x10^7 N and a mass of 2.75x10^6 kg , and drag is 1/8 as big as it's weight. If it starts from rest, how fast will it be going 10 seconds after it started accelerating?
9.75 m/s
What is the difference between kinetic and static friction
kinetic=sliding
static=not sliding
A person with mass 60 kg is in an elevator moving upward and is speeding up at 1.5 m/s2. How big is the normal force on the person?
678 N
A force of 50 N is used to push a box across the floor. If the box accelerates at 0.7 m/s^2, how big is the coefficient of kinetic friction?
0.704
A rocket takes off from earth going straight up with a force of thrust=3.3x10^7 N and a mass of 2.75x10^6 kg , and drag is 1/8 as big as it's weight. How far will it have travelled in 10 s?
48.75 m
What happens to an object when forces are balanced, what happens when they are unbalanced?
balanced=no change in motion (acceleration = 0)
unbalanced=acceleration
A car of mass 1050 kg is going to be pulled by a really strong rope. Ignore friction and drag. How much tension must the rope be able to withstand if the car is acceleration at 1.2 m/s^2 horizontally?
1260 N
Suppose you run as fast as you can and then slide merrily across a long patch of ice. The coefficient of kinetic friction between your pants and the ice is 0.1. What will your acceleration be as you slide across the ice?
-0.98 m/s^2
A car of mass 1050 kg is going to be pulled by a really strong rope. Ignore friction and drag. How much tension must the rope be able to withstand if the car is acceleration at 1.2 m/s^2 vertically?
11550N
What is the difference between the Force of friction and the Coefficient of Friction?
The force of friction is the coefficient of friction x the normal force. The coefficient of friction tells us how slippery or how much grip a surface has
If a rocket takes off from earth going straight up with a force of thrust=4.3x10^7 N and a mass of 2.75x10^6 kg , and drag is 1/6 as big as it's weight, what is the objects acceleration?
4.20 m/s^2
A force of 40 N is required to start a 6 kg box moving across a horizontal floor (meaning that the acceleration is equal to zero). What is the coefficient of static friction between the box and the floor?
0.680
A person with mass 60 kg is in an elevator moving upward and is slowing down at -1.5 m/s2. How big is the normal force on the person?
498 N
the force of gravity!!!!! mg
A fisherman yanks a fish out of the water pulling straight up. The fish accelerates at 3.5 m/s^2. Unfortunately, the string snaps because the maximum force it can withstand is 32N. What is the mass of the fish?
2.4 kg
You are going to push a chair of mass 5 kg across the floor. The coefficient of kinetic friction is 0.15. How much force do you need to push with in order to have an acceleration of 0.5 m/s2
9.85 N
A rocket of mass 2,750,000 kg fires it's engines with a force of 5.3x10^7N to take off from earth. What is the rockets acceleration? If it starts from rest, how fast will it be going 10 seconds after it started accelerating? How far will it go during the 10 seconds?
9.47 m/s^2
94.72 m/s
473.63 m