Conservation of Energy Calculation Problems
This topic is part of the HSC Physics course under the section Forces, Acceleration and Energy.
HSC Physics Syllabus
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apply the special case of conservation of mechanical energy to the quantitative analysis of motion involving:
Energy Conservation Problems
The following video walks through 5 common calculation problems on the law of conservation of energy and conservation of mechanical energy.
Watch the video for step-by-step solutions to the following questions
Example 1
Consider a ball is thrown vertically upward in a vacuum (no air resistance).
(a) Describe the changes in the ball’s kinetic energy, potential energy and mechanical energy.
(b) What speed is required to throw a ball vertically upwards to reach a maximum height of 50 m?
Example 2
A box slides down a hill that is 250 m tall with an initial velocity of 10 m/s to the right. Assuming no friction and air resistance, what is the final speed of the box when it reaches the bottom of the hill?
Example 3
An 800 kg car travels along a horizontal road with an initial speed of 20 m/s. The driver lets the car come to a complete stop without braking over a distance of 160 m. What is the coefficient of kinetic friction between the tyres of the car and the road?
Example 4
A trolley rolls down a frictionless track with an initial speed of 10 m/s at A, 20 m above the ground. It reaches its lowest point at B (ground) before travelling upwards to reach C. The speed of the trolley at C is 8 m/s.
(a) What is the speed of the trolley at B?
(b) What is the height of C above the ground?
Example 5
A 500 kg car moving to the right at 30 m/s collides with another 800 kg car moving to the left at 20 m/s. After the collision, the 500 kg car is moving to the left at 2 m/s while the 800 kg car comes to a complete stop.
How much heat and sound energy are produced during this collision?