Work
What is work's formula
What is W=FD
What is forces
What is any interaction that, when unopposed, will change the motion of an object
Power's formula is
What is P=W/T
Momentum is
What is the product of the mass and velocity of an object
What is Energy?
What is the capacity to do work
The label for work is
What is joules (J)
Force is measured in
What is Newtons (N)
Power in physics is the rate at which _____ is used
What is energy
Momentum could be shown as
kg m/s
What unit is energy measured in?
What is Joules (J)
You apply a force of 16 N to a dresser and move it 4.0 m. How much work did you do on the dresser?
What is 64 J
W=FD
W=(16N)(4m)
W=64 J
An object with a mass of 10 kg is accelerating at 4 m/s^2. What is the net force on the object?
What is 40 N
F=ma
F=(10 kg)(4 m/s^2)
F=40 N
If it takes 45 J of work to move a rock 13 meters in 9 seconds, what is the power?
What is 5 Watts
P=W/T
P=45 J/9 s
P=5 Watts
The momentum of a 23 kg softball moving at 33 m/s is
What is 759 kg m/s
P=mv
P=(23 kg)(33 m/s)
P=759 kg m/s
How many different types of energies are there?
What is 10
A 450 newton student runs up a flight of stairs 6 m high in 13 seconds. The student takes 9 seconds to run up the same flight of stairs during a second trial. The work done by the 450 N student running up the stairs in is first trial is
What is 2700 J
W=FD
W=(450 N)(6 m)
W= 2700 J
A work of 30 J is used to push along a block along the floor a difference of 3 m. How much force is used on the block?
What is 10 N
F=W/D
F=30 J/ 3 m
F=10 N
A box has a work of 400 J and moves to a different 4 m in 16 s. The power that this box has is
What is 25 Watts
P=W/T
P=400 J/16 s
P=25 Watts
A 2.0 Kg skateboard is moving with a velocity of 1 m/s. The skateboard crashes into another skateboard which is initially at rest. After the 2 crashed they move together at a velocity of .75 m/s. The total momentum of this frictionless system is
What is the same before and after the crash
An object weighing 55 kg is moving at a speed of 11 m/s. The objects kinetic energy is
What is 6,655 J
KE=mv^2
KE= (55 kg)(11 m/s)^2
KE= 6,655 J
Person A lifts up a 60 newton box from the floor to a height of .50 m in 5 seconds. Person B lifts a 50 Newton box from the floor to .60 m in 4 seconds. Who has more work done Person A or Person B
What is equal amount of work done
Person A: W=FD
W=(60 N)(.50 m)
W= 30 J
Person B: W=FD
W=(50 N)(.60 m)
W= 30 N
A 4,200 kg object accelerates at a rate of 4,500 m/s^2. The force on this object is
What is 18,900,000 N
F=MA
F=(4,200 kg)(4,500 m/s^2)
F= 18,900,000 N
What is the power needed to change has a work of 1700 J shopping utility vehicle from 16 m/s to 50 m/s in 2 seconds. The power needed to change the speed is
What is 850 Watts (W)
P=W/t
P=1700 J/2 s
P= 850 W
A 7 kg block slides along a frictionless surface at 20 m /s for 6 seconds. The magnitude of the block is
What is 140 kg m/s
P=mv
P=(7 kg)(20 m/s)
P=140 kg m/s
What is the efficiency of a machine when the input is 734 J and the output is 155 J?
What is 21.1%
Energy Effieciency =useful energy output/ energy input x100
EE=155 J/ 734 J x100
EE=21.1%