Definitions/
T OR F
T OR F
Kinetic Energy
Energy due to motion.
An engine preforms 280 J of work in 90 seconds. How much power does the engine have?
P=w/t
P=280 J/90s
P= 3.11 W
A 7 Kg box is laying 12m high on a table with 36 J of work. How much force does the box have?
W=Fd
36 J=F(12m)
F=3N
A car travels a distance of 160 m with a speed of 24 m/s for 8s. While driving the car stops at the stop sign. What is the cars acceleration?
Vf^2=Vi^2+2ad
(0 m/s)^2=(24 m/s)^2+2(a)(160m)
0=576+2a(160)
-576=2a(160)
-3.6=2a
a=-1.8 m/s^2
True or False
The force of friction always opposes motion.
Truth
What is the magnitude of the velocity of a 65 Kg object that has a momentum of 400 kilogram meter per second?
P=mv
400Kgm/s=(65Kg)v
v= 6.15m/s
What net force would accelerate a 500 kilogram truck at 5.2 meters per second square?
FNET=ma
FNET=(500kg)(5.2m/s^2)
FNET= 2600 N
A dog initially runs at 20 m/s for 8s with an acceleration of 12 m/s^2. What is the dogs final speed?
Vf=Vi+at
Vf=20m/s+(12m/s^2)(8s)
Vf=20+96
Vf=116m/s
True Or False
Gravity is a very strong force
False
A 4 Kg basketball travels at a speed of 16 meters per second. What is the basketball’s kinetic energy?
KE=1/2mv^2
KE=1/2(4Kg)(16m/s)^2
KE=512 J
A 200 kilogram car travels for 40 meters and has a force applied of 500 Newtons and a force of friction of -80 Newtons. What is the net force?
FNET=FAPP+Ff
FNET= 500 N+ -80 N
FNET= 420 N
A Great Neck North student travels around the school with a speed of 5m/s. Although before he was walking he stopped to pick up his backpack for 66 s. In total the student traveled a distance of 52m. What is the acceleration?
Vf^2=Vi^2+2ad
(5m/s)^2=(0m/s)^2+2a(52m)
25=2a(52)
2a=0.48
a=0.24m/s^2
Definition for a Direct Graph Relationship
Two variables that do the same thing (if one increases the other increases)
A 5 Kg child climbs a ladder. The child stops climbing the ladder at a distance of 3m with a force of 12N. How much work does the child do?
Fg=mg W=Fd
Fg=(5Kg)(-9.81m/s^2) W=(-49.05N)(3m)
Fg= -49.05 N W=-147.15 J
A 26 kilogram object has a net force of 350 newtons. What is the acceleration of the object?
FNET=ma
350 N=(26Kg)a
a=13.46 m/s^2
A ball is laying on a table with a height of 32m then falls off.
d=vit+at^2
32m=(0m/s)(t)+(-9.81m/s^2)(t)^2
3.26=t^2t=1.8s
Definition for Equilibrium
When forces are equal/balenced
An object is placed on a spring with a spring constant of 112 newtons per meter that stores 10 joules of energy. How far does the spring compress?
PEs=1/2Kx^2
10 J=1/2(112N/m)x^2
10 J= (56) X^2
0.18=x^2
x=0.42mA steel block slides horizontally with a force of 35 N at a constant speed on a steel surface. What is the weight if the box?
FNET=FAPP+Ff
0 N=35 N+Ff
Ff=-35 N
Ff=μFn
-35 N=(.57)Fn
Fn=61.4 N
Fn=-Fg
Fg= -61.4 N
An object travels downwards for 3s in a distance of 16m. What is the initial and final speed of the object?
d=Vit+1/2at^2
16m=Vi(3s)+1/2(9.81m/s^2)(3s)^2
16=Vi(3)+44.15
-28.15=Vi(3)
Vi=-9.38 m/s
Vf=Vi+at
Vf=(-28.15m/s)+(9.81m/s^2)(3s)
Vf=1.28 m/s