Mechanics | Relativity Answers

RESISTANCE OF A HEADLIGHT

What is the resistance of an automobile headlight through which 2.50A flows when 12.0V is applied to it?

Objects whose masses are 300 gm and 200 gm, respectively, are attached to opposite

ends of a light string passing over a light frictionless pulley, Find (a) the acceleration

or the system and (b) the tension in the string.

A 50 kg mass moving to the right at 8 m s−1 collides with a 25 kg mass moving to the right at 3 m s−1. After the collision, the velocities of the masses are v1 and v2, where v2 > v1 and 15% of the original kinetic energy is lost during the collision. Assume that no external forces are acting.

(a) Show that v2 = 19 − 2v1.

(b) Show that 3v 2 1 − 38v1 + 100 ≈ 0 is a good approximation of the equation for v1.

(c) Calculate v1 and v2.

(d) What happened to the 15% lost energy? 

A bus travelling at a constant velocity of 72km/he passes a stationary car. After a time lapse of 1/6 minutes, the car accelerates uniformly at 3m/s^2 to reach a speed of 108km/hr and maintains this speed afterwards. Draw the speed-time graph and find when and where the car overtakes the bus.

The most powerful tugboats in the world are built in Finland. These boats exert a force with a  magnitude of 2.85 x 106 N. Suppose one of these tugboats is trying to slow a huge barge that has  a mass of 2.0 x 107 kg and is moving with a speed of 3.0 m/s. If the tugboat exerts its maximum  

force for 21 s in the direction opposite to that in which the barge is moving, what will be the  change in the barge’s momentum? How far will the barge travel before it is brought to a stop?  

Other things being equal, would it be easier to drive at high speed around an unbanked horizontal curve on the moon than drive around the same curve on the earth?

A car is traveling in uniform circular motion on a section of road whose radius is r. If the road is slippery and the car is just on the verge of sliding. If the car's speed is doubled, what would be the smallest radius to stop the car from sliding?

An elastic wire with the undistorted length of L0= 80cm and the elastic constant k= 150 N/m is cut in half, L0' = 40cm. Under the action of a deforming force, F=6N is lengthened by how much?

A 50kg student walks and runs up a set of stairs that has a vertical height of 1.5meters. It takes 3 seconds to walk up and 1 second to run up. Compare the work and power done walking and running.