A froghopper is a small insect which can launch itself upwards with an acceleration of about 400 times gravity. In the first stage of its jump, while its feet are in contact with the ground, the froghopper accelerates to reach a top speed of 4.0m/s. This is reached when its body is 2mm above the ground. After losing contact with the ground, acceleration is then only due to gravity. Calculate the following (ignoring air resistance):
(a) The time to reach a maximum height
(b) The maximum height reached
(c) The speed on hitting the ground
A person wearing a seatbelt has a good chance of surviving a car crash if the magnitude of the deceleration is no more than 300 m/s2. Over what duration must a crash occur for the occupants of the car to survive being brought to a standstill from an initial speed of 100km/hr?
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