Mechanics | Relativity Answers

A bungee jumper jumps (with no initial speed) from a tall bridge attached to a light elastic cord (bungee cord) of unstretched length L. The cord first straightens and then extends as the jumper falls. This prevents her from hitting the water! Suppose that the bungee cord behaves like a spring with spring constant k = 80 N/m. The bridge is h = 110 m high and the jumper's mass is m = 40 kg. Use g = 10 m/s2.
(a) What is the maximum allowed length L of the unstretched bungee cord (in m) to keep the jumper alive?
(b) Before jumping, our jumper verified the spring constant of the cord. She lowered herself very slowly from the bridge to the full extent of the cord and when she is at rest she measured the distance to the water surface. What was the measured distance (in m)?

The resultant of two vectors A and B is perpendicular to vector A and has the magnitude 24 cm.If the sum of magnitudes of vector A and vector B is 32 cm,then their magnitudes are
1) 5 cm, 27 cm
2) 7 cm ,25 cm
3) 14 cm,18 cm
4) 10 cm,22 cm

A cart is moving horizontally along a straight line with constant speed of 20 m/s.A projectile is to be fired from the moving cart so that it returns to the same cart after the cart has moved 60 m.The speed with which the projectile must be fired with respect to the cart is
1) 5 m/s
2) 10 m/s
3) 15 m/s
4) 20 m/s

A boy aims a target at a horizontal distance of 60 m.If the muzzle speed of bullet is 600 m/s, then the height above the target which he should aim is
1) 5 cm
2) 10 cm
3) 15 cm
4) 20 cm

A ball rolls off the top of stair way with a horizontal velocity of magnitude 2 m/s.The steps are 10 cm high and 20 cm wide. if g =10 m/s^2 ,then the ball hits first the edge of
1) first step
2) second step
3) third step
4) fourth step

In a performance test, each of two cars takes 8.3 s to accelerate from rest to 29 m/s. Car A has a mass of 1361 kg, and car B has a mass of 1871 kg. Find the net average force that acts on (a) car A and (b) car B during the test.

A 12,400-kg airplane launched by a catapult from an aircraft carrier is accelerated from 0 to 210km/h in 4 s. How many times the acceleration due to gravity is the airplane's acceleration?

A frog falls from a rain forest tree. If we ignore wind resistance how much time does it take the frog to fall a distance of 12 meters?

A ball is thrown with an angle of 12 degrees to the horizon with a speed of 15m/s. What are it's vertical and horizontal components

calculate the component of a force of 200N AT A DIRECTION OF 60 DEGREE TO THE FORCE.