Mechanics | Relativity Answers

A 3.3 kg block slides down a 6.1 m long ramp with a 30° angle of inclination. If the coefficient of kinetic friction between the block and the ramp is 0.49, what is the work done on the block by friction as it slides all the way down?

A 2.6 kg bird flies 46 m off the ground. What is the bird’s gravitational potential energy?

A 59,300 kg plane moves at 254 m/s. What is the plane’s kinetic energy?

A fan motor uses 8310 J of energy in 9.44 s. This energy is used to accelerate a 8.12 kg blade to 19.7m/s in 3.10 s. What is the efficiency of the fan? Leave your answer as a decimal.

A 47.3 kg wheelchair rolls down a 17.4 m long ramp with an angle of inclination of 20.3° in 7.1 s. What is the power of gravity on the wheelchair?

1) (a) Does motion affect the rate of a clock as measured by an observer moving with it? (b) Does motion affect how an observer moving relative to a clock measures its rate? 2) To whom does the elapsed time for a process seem to be longer, an observer moving relative to the process or an observer moving with the process? Which observer measures the interval of proper time? 3) To whom does an object seem greater in length, an observer moving with the object or an observer moving relative to the object? Which observer measures the object’s proper length? 4) Prove that for any relative velocity v between two observers, a beam of light sent from one to the other will approach at speed c (provided that v is less than c, of course). 

Given event A, mark examples of events B-F that satisfy these criteria. A material object travels from A to B. An object traveled from C to A. A ray of light emitted at A is received at D. A ray of light emitted at E is received at A. F can have no possible cause-and-effect relationship with A. 

Draw spacetime diagrams of: (1) a box with a particle bouncing back and forth inside it, (2) a ray of light being absorbed by a leaf on a tree, (3) an atomic nucleus splitting up into two parts (fission), (4) a cloud of gas collapsing gravitationally to form our solar system.  

A golf ball is at rest on a horizontal surface 1.3m from a hole 

A golfer hits the ball so that it moves horizontally with an initial velocity of 1.8 ms power of -1.The ball experiences a constant deceleration of 1.2 ms power od -2 as it travels to the hole .Calculate the velocity of the ball when it reaches the edge of the table 

As the parachute-spacecraft system decelerates it falls through a vertical distance of 49m and loses 2.2 x 10 to the power of 5 J of kinetic energy.

During this time , 3,3 x 10 to the power of 5 J of energy is transferred from the system to the atmosphere.The total mass of the system is 610 kg 

Calculate the acceleration due to gravity as it falls through this distance