A 15 kg block is firmly attached to a very light horizontal spring (k = 550 N/m) and resting on a smooth horizontal table. Suddenly it is struck horizontally by a 3 kg stone travelling with a velocity of 8 m/s to the right, whereupon the stone rebounds at 2 m/s to the left. Find the maximum distance that the block will compress the spring after the collision.

# Impulse & Momentum

# Human-Powered Helicopter

A student builds a human-powered helicopter (HPH). It is a helicopter powered by one person carried on board and the power is generated by pedaling.

This human-powered helicopter has the following parameters: diameter of helicopter rotor blades is 15 meters and total mass is 100 kg. The air density 1.3 kg/m^3.

Can the HPH take off?

# Event violates the law of conservation …

# A cannon ball.

# To what height does the m2 rebound ? The Collision problem.

A ball with small mass m2 placed on a ball with large mass m1. The bottom of the m1 is a height h above the ground and the bottom of the m2 is a height h + d above the ground. The balls are dropped. To what height does the m2 rebound?

Note. Please consider the balls are separated by a very small distance at the beginning, m1 is much larger than m2 and assume that the balls bounce elastically.

# Collision. Work. Power. Question 1

Question. Source. Yahoo ! Answers !

mass of trolley = 800 kg

Initial velocity of Issac’s car = 30 m s–11- Calculate the final velocity of the car and trolley together.

2- Mike’s car has a long crumple zone. Explain in detail why having this crumple zone would make a difference during impact. what are the ideas of velocity before and after the impact.

Issac’s car is towed away by a tow truck. The rope attached to the car makes an angle of 50 with the horizontal. The rope pulls the car with a force of 900N. The car moves a distance of 40 m along the horizontal road during a time of 20s.

3- What is the work done by the tow truck on the car.

4- What is the power produced by the tow truck while it is moving the car.

It is Perfectly inelastic collision .

M1*V1=(M1+M2)*UM1 – mass of Issac’s car

V1 – Initial velocity of Issac’s car

M2 – mass of trolley

U – final velocity of the car and trolley together1700*30=(1700+800)*U So, U = 20.4 m/s

2) than zone longer, Mike’s car safety

Source:

http://en.wikipedia.org/wiki/Crumple_zon…

3)

W=F*D*COS (A)

W – work

F – force

D- distance

A – angle

W=900*40*COS(50)=23140.35 J

4)

P=W/t

P – Power

t – time

P=23140.35/20=1157.02 Watt