1.A car is travelling at high speed along a country road when all of a sudden, a tree jumps out of nowhere. The driver slams on the brakes, reducing the speed of the car somewhat, before crashing into the tree
Describe the energy transformations that take place (from the moment the driver presses the brakes) if the collision is elastic (the car bounces off the tree)
Now describe the energy transformations that take place if the car is fitted with a crumple zone and comes to a stop upon hitting the tree (inelastic collision).
2. Calculate the work done by the engine in a car of mass 1000kg in accelerating the car from rest at 2ms¯2 for 20seconds. (hint: you need to calculate the distance the car travels in this time)
3. During the pumping cycle of a heartbeat, blood is ejected from the aorta at 0.14m/s.
Given at 100g of blood are pumped in each heartbeat, calculate the kinetic energy of the ejected blood.
If a person’s heart beats 70 times per minute, how much kinetic energy is carried from the heart in 1 day.
4. an archer’s arrow is shot vertically upwards with an initial velocity of 20m/s. use energy conservation to determine how high it will fly.
5. water falls from a cliff and is found to be at 1?C hotter at the base of the cliff than the top.
List all the energy changes in this situation
Explain why the water has heated up.
6. a 5kg dumb-bell is dropped by an athlete from a height of 3m.
What is its initial potential energy?
Whats is the speed of the dumb-bell just before it hits the ground?
What have you assumed in part b)?
What would the answer to part b) change if the dumb-bell were twice the mass?
7. a child of mass 15kg is pushed down a slide with an initial speed of 2m/s. the child was initially at a vertical height of 5m above the ground. Friction with the slide is negligible.
Draw a fully labelled diagram of the situation.
Determine the initial kinetic energy of the child.
Calculate the total energy of the child at the top of the…