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Calculate the spring constant of each spring in the mattress.
Give the unit.
in collisions is a consequence of Newton’s third law of
motion.
A student is using a ‘Newton’s Cradle’. This consists of a set of identical solid metal balls hanging by threads from a frame so that they are in contact with each other.
He initially pulls one ball to the side. He releases the ball, it collides with the nearest stationary ball and stops. The ball furthest to the right immediately moves away. The middle three balls remain stationary.
(a) Explain what measurements the student would take and describe how he would use them to investigate whether momentum had been conserved in this event. [4]
(b) The student makes the following observations:
• the ball on the right returns and collides with a similar
result; this repeats itself a number of times
• after a while, the middle balls are also moving
• shortly afterwards, the balls all come to rest.
Discuss these observations in terms of energy
Mycobacteria move by ejecting slime from nozzles in
their bodies.
Explain the physics principles behind this form of propulsion.
4 An ice skater and his coach begin stationary and push apart from each other with a force of 75 N. The skater has a mass of 64 kg, whilst the coach weighs 804 N.
If the skater moves off to the left with a speed of 3.6 m s−1, what is the velocity of the coach?
In a stunt for an action movie, the 100 kg actor jumps from a train that is crossing a river bridge.
On the river below, the heroine tied to a small boat is drifting towards a waterfall at 3 m s−1. The small boat and heroine have a total mass of 200 kg.
(a) If the hero times his jumps perfectly so as to land on the small boat, and his velocity is 12 m s−1 at an angle of 80 º to the river current, what will be the velocity of the small boat immediately after his landing? Draw a vector diagram to show the momentum addition. Ignore any vertical motion.
(b) If the waterfall is 100 m downstream, and the hero landed when the small boat was 16 m from the bank, would they drop over the fall? Assume the velocity remains constant after the hero has landed. The small boat and the waterfall are on the same side of the bridge as he jumps.
A boy in a stationary boat on a still pond has lost his oars in the water. In order to get the boat moving again, he throws his rucksack horizontally out of the boat with a speed of 4 m s−1.
Mass of boat = 60 kg; mass of boy = 40 kg; mass of rucksack = 5 kg
(a) How fast will this action make the boat move?
(b) If he throws the rucksack by exerting a force on it for 0.2 s, how much force does he exert?
A movie stuntman with a mass of 90 kg stands on a stationary 1 kg skateboard. An actor throws a 3.4 kg brick at the stuntman who catches it. The brick is travelling at 4.1 m s−1 when caught.
starting from rest. In the first second, it travels ____?
