Physics Test Three Examples Flashcards
A person carries a bucket of water with Fw=16N a distance of 10m. How much work was done on the bucket to carry it?
W=0
A person picks up a 16N bucket of water from the ground to a distance of 3m. How much work was done on the bucket to lift it? (Assume Constant velocity)
W=48J
A person picks up a 16N bucket of water from the ground to a distance of 3m. How much work is done by gravity when the bucket is lifted?
W= -48J
Find the work done by an applied force, Fa, to move a box along the floor where the coefficient of kinetic friction is .45, if Fa is 15 degrees above the horizontal and the box moves at a constant velocity. Mass of the box=5Kg, Distance=6m
W=118J
A spring is originally stretched by 4cm by a 10Kg mass as it hangs vertically. If the same string is compressed horizontally 6cm, how much work was required to compress the string?
W=4.4J
How much power is needed to lift a 6Kg box a distance of 20m in 15seconds?
P=78 Watts
A car with a mass of 200Kg and a speed of 20m/s coasts to rest in a distance of 100m. What is the average frictional force on a car?
F= -4000N
You have a box on a table that is .5m above the ground. You want to move the box to a bookshelf that is 2m above the ground. What is the change in potential energy?
Change in PE= mg(1.5)
You are on the second floor of a building that is 5m above the first floor, and you have a box on a table that is .5m above the ground. You want to move the box to a bookshelf that is 2m above the ground. What is the change in potential energy?
Change in PE= mg(1.5)
You drop a rock off a bridge at 10m high from rest. How fast is it going when it hits the water?
V= 14m/s
Find the speed of a box of mass, m, at the bottom of a 5m ramp that has an incline of 25 degrees. The box starts from rest.
V=6.43m/s
A mass of 5Kg sits on a spring (k=500N/m) that has been compressed 8cm. If the spring is released and the mass is shot upward, find the mass’ max height.
h= .03m
A car with Vo=20m/s and m=1200Kg hits a tree. If it takes 1.5seconds for the car to stop, find the average force of the tree on the car.
Favg= -1.6x10^4N
A ball with m=.5Kg hits a wall with a speed of 10m/s. The ball rebounds with the same speed. If the impact lasts .3seconds, what is the force of the wall on the ball?
F= -33N
You are a member of an alpine rescue team and must get a box of supplies, with mass 2.70 kg , up an incline of constant slope angle 30.0 ∘ so that it reaches a stranded skier who is a vertical distance 3.30 m above the bottom of the incline. There is some friction present; the kinetic coefficient of friction is 6.00×10−2. Since you can’t walk up the incline, you give the box a push that gives it an initial velocity; then the box slides up the incline, slowing down under the forces of friction and gravity. Take acceleration due to gravity to be 9.81 m/s^2. Use the work-energy theorem to calculate the minimum speed v that you must give the box at the bottom of the incline so that it will reach the skier.
Vo=8.32m/s
