Mechanics | Relativity Answers

A dog jogs 4m down a hall in 2 seconds and jogs 3m down a perpendicular hall in 1.5 seconds. What was its average speed? What was its average velocity?

Lex Luthor drops Lois Lane from the roof of a building which has a height of 180m. Five seconds later, superman pushes himself off of this roof with an initial speed vo directed downwards towards Lois. After his feet leave the roof, superman accelerates downwards at the same rate as any other freely-faliling object.
How long after he leaves the roof does it take superman to catch up to Lois?
What must be the minimum value of vo so that superman can catch Lois just as they reach the ground?

6. Curly, Moe, and Larry are 3 lab students tasked with finding the speed of a small, battery powered car. They decide to lay out a course for the car by putting 2 pieces of tape on the floor a known distance apart, timing how long between the time the car passes the first piece of tape and then the second tape. They will calculate speed by dividing the distance between the tapes by the time it took to make the trip. Curley votes to put the two pieces of tape 1 meter apart because it is easy and the distance really does not make a difference. He is outvoted by Moe and Larry, who vote for a distance of 5 meters, arguing that they make the same error in timing no matter the length of the course and dividing this error by a larger distance will give them a more accurate answer. With whom do you side? Defend your answer with a quantitative argument. You might want to estimate a timing uncertainty? Maybe assume some time?

A car travelling with a constant acceleration has a velocity of 6m/s at a given instant. In the next minute it travels 3km. Find its acceleration and the velocity after a minute

A baseball is dropped from the roof of a building. After some time, it flies past a window of height 2.20m. if the time it takes the baseball to fall past the window is 1/3s, how far above the window is the roof?

a small block of mass m slides along a friction less track as shown .calculate the height h at which mass must be released on the track to be able to go round the track or radius R .if h= 5R, what is the reaction exerted by the track on the block when it is at point A ,B and C

A solid sphere of mass 100 kg and radius 10 m moving in a space becomes a circular disc of radius 20 m in one hour. Then the rate of change of moment of inertia in the process is

A ball is thrown upward from ground with an initial speed of 25 m/s, at the same instant, another ball is dropped from a building 15 meters high. a.) How long will the two balls be at the same height? b.) Calculate the height where the two balls meets.

two perfectly elastic balls A and B of masses 2kg and 4kg respectively move in opposite directions with velocities of 4m/s and 1m/s. find the final velocities of the two balls after collision

1. Kinetic energy is conserved in an elastic collision by definition. Show, using the Galilean
transformation equations, that if a collision is elastic in one inertial frame it is elastic in
all inertial frames.
2. An electron whose speed relative to an observer in a laboratory is 0.800c is also being
studied by an observer moving in the same direction as the electron at speed of 0.500c
relative to the laboratory. What is the kinetic energy (in MeV) of the electron to each
observer ?
3. An observer on a spacecraft moving at 0.700c relative to the earth finds that a car takes
40.0min to make a trip. How long does the trip take to the driver of the car?