Physics Work,Power & Energy Level: High School
A 60 kg skydiver moving at terminal speed falls 50 m in 1 s . What power is the skydiver expending on the air ?
Physics Work,Power & Energy Level: High School
Inelastic collision
A gun is fired vertically into a m = 1.46 block of wood at rest on a thin horizontal sheet directly above it , as shown in the figure at “click here” . If the bullet has a mass of 21.0 g and a speed of v = 3210 m/s , how high will the block rise into the air after the bullet becomes embedded in it ?
Physics Work,Power & Energy Level: High School
Collision
Two carts of equal mass , m = 0.220 kg , are placed on a frictionless track that has a light spring of force constant k = 54.8 N/m attached to one end of it, as in the figure at “click here” . The red cart is given an initial velocity of Vo = 3.39 m/s to the right , and the blue cart is initially at rest .(a) If the carts collides elastically, find the magnitude of the velocity of the red cart just after the first collision .
(b) Find the magnitude of the velocity of the blue cart just after the first collision .
(c) Find the maximum compression of the spring .
Physics Work,Power & Energy Level: High School
Elastic collision
A block of mass m = 2.32 kg slides down an infinite = 27.8 degree incline which is h = 3.52 m high . At the bottom , it strikes a block of mass M = 7.44 kg which is at rest on a horizontal surface , as seen in figure at “click here" (Assume a smooth transition at the bottom of the incline .) If the collision is elastic , and friction can be ignored ,(a) Determine the speed of the smaller block after the collision .
(b) Determine the speed of the bigger block after the collision .
Physics Work,Power & Energy Level: High School
Conservation of linear momentum and inelastic collision
An 8.56 g bullet is fired into a 255 g block that is initially at rest at the edge of a table of h = 1.04 m height (see the figure at “click here”) . The bullet remains in the block, and after the impact the block lands d = 1.87 m from the bottom of the table . Determine the initial speed of the bullet .
Physics Work,Power & Energy Level: High School
would it take him to lift a 200 kg load . if the winch has an efficiency of 90 percent , and the rate at which can do work is 0.8 hp ?63 s
A roofer lifts supplies to a height of 20 m with a hand-operated winch . How long 73 s
Physics Work,Power & Energy Level: High School
A 200 gram mass is attached to the end of a spring causes it to stretch 5.0 cm. If another 200-g mass is added to the spring , the potential energy of the spring will beTwice as much .
The same.
4 times as much
.3 times as much.
Physics Work,Power & Energy Level: High School
Assuming negligible friction , what spring constant would be needed by the spring in a “B-B gun” to fire a 10 gram pellet to a height of 100 meters if the spring is initially compressed 10 cm ?2.0 N/cm
200 N/m
20 N/m
Physics Work,Power & Energy Level: High School
The total mechanic energy of a systemIs equally divided between kinetic energy and potential energy.
Is constant, only if conservative forces act.
Is either all kinetic energy or all potential energy, at any one instant.
Can never be negative.
Physics Work,Power & Energy Level: High School
A gun is fired vertically into a 2.40 kg block of wood at rest directly above it . If the bullet has a mass of 22.0 g and a speed of 340 m/s . how high will the block rise into the air ?
Physics Work,Power & Energy Level: High School
Collision
An 8.00 kg mass moving east at 14.3 m/s on a frictionless horizontal surface collides with a 10.0 kg object that is initially at rest . After the collision , the 8.00 kg object moves south at 3.50 m/s .(a) What is the velocity of the 10.0 kg object after the collision ?
(b) What percentage of the initial kinetic energy is lost in the collision ?
Physics Work,Power & Energy Level: High School
Inelastic Collision
A railroad car of mass 2.80 104 kg moving at 3.00 m/s collides and couples with two coupled railroad cars , each of the same mass as the single car and moving in the same direction at 1.20 m/s .(a) What is the speed of the three coupled cars after the collision ?
(b) How much kinetic energy is lost in the collision ?
Physics Work,Power & Energy Level: High School
Calculate(a) the escape velocity of a rocket off the earth’s surface and
(b) the escape velocity of a rocket of the moon assume g at earth’s surface to be 9.81 m/s 2 and 5 at the moon surface 1.67 m/s^2 hint use work-energy theorem .
Physics Work,Power & Energy Level: High School
Calculate(a) the work that a student must do in order to carry a 25.0 kg backpack up a hill of height (40.0 meters)
(b) calculate the work done by gravity
(c) calculate the net work done the back pack .
Assume climber s motion is smooth with no acceleration in climbing up the hill .
Physics Work,Power & Energy Level: High School
(a) Does the string that supports a pendulum bob do work on the bob as it swings to and fro ?(b) Does the force of gravity do any work on the bob ?
