Iolani Invitational — Hovercraft

Your hovercraft is at rest and will stay at rest unless acted upon by a(n) ____ force(s).

Which of the following is not a contact force?

Impulse has units of ____ and is dimensionally equivalent to ____.

You are impounding your hovercraft. Your hovercraft is in a box. The total mass of the box and your hovercraft is 10 kg. You set your box on the floor. The team from Troy HS impounds a box containing their super lightweight hovercraft on top of your box. The total mass of the Troy HS hovercraft and box is 5 kg. What is the force exerted by the floor on your 10 kg box?

How much force is required to keep a 1.0 kg hockey puck moving at constant velocity?

A net force F acts on a mass m and produces an acceleration a. What acceleration results if a net force 2F acts on mass 4m?

If your hovercraft accelerates from rest to 20 m/s in 5.0 seconds, what is the acceleration?

If your hovercraft accelerates from rest to 20 m/s in 5.0 seconds, how much distance did it travel while accelerating?

At t = 0, your hovercraft is located at x = 25 m and has a velocity of 15 m/s in the positive x direction. The acceleration of your hovercraft varies with time as shown in the diagram below. What is the velocity of your hovercraft at t = 5.0 s? Show your work.

Your hovercraft has the maximum ground footprint of 40.0 cm x 40.0 cm. You have decided to maximize your mass score and therefore plan to have your hovercraft carry all 16 rolls of pennies, which have a total mass of 2.00 kg. The expected mass of your vehicle is 1.00 kg. Assuming the air pressure beneath your craft is uniform, what is the minimum static pressure that your blower must produce? Show your work.

Your hovercraft did not perform well. You are mad. You decide to throw it off the roof of the parking garage, a height of 20 m from the ground. You throw it with a horizontal velocity of 30 m/s and vertical velocity 0.0 m/s. Neglecting air resistance, what is your hovercraft's horizontal and vertical velocity when it hits the ground? Show your work.

A ball is thrown vertically upward with an initial speed of 20 m/s. 2.0 seconds later, a stone is thrown vertically (from the same initial height as the ball) with an initial speed of 24 m/s. At what height above the release point will the ball and stone pass each other? Show your work.

You are lazy and want to use a conveyor belt to transport your hovercraft to impound. Your hovercraft is in a box. You drop the box onto a conveyor belt which is moving at 2.0 m/s. If the coefficient of friction between the box and the belt is 0.30, how long before the box moves without slipping? Show your work.

When an automobile moves with constant velocity the power developed is used to overcome the frictional forces exerted by the air and the road. If the power developed in an engine is 50.0 hp, what total frictional force acts on the car at 55.0 miles per hour (24.6 m/s)? One horsepower (hp) equals 746 W. Show your work.

Write the basic equation for kinetic energy of an object as a function of its velocity.

Choose one of the underlined terms for each. Circle the correct term. Momentum is a (scalar/vector) quantity and kinetic energy is a (scalar/vector) quantity.

For an object to have momentum, it must have nonzero

A surprising demonstration involves dropping an egg from a third-floor window to land on a foam-rubber pad 5.0 cm thick without breaking. If a 56 gram egg falls 12 m, and the foam pad stops the egg in 6.25 ms, by how much is the pad compressed (in cm)? Show your work.

A pitcher claims he can throw a baseball with as much momentum as a 3.00 g bullet moving with a speed of 1500 m/s. A baseball has a mass of 0.145 kg. What must be its speed if the pitcher's claim is valid? Show your work.

Your 25 kg hovercraft is at rest. It is bumped by Troy HS's 35 kg hovercraft traveling at 5.0 m/s. Directly after the collision, the velocity of your hovercraft is 7.0 m/s and the Troy hovercraft comes to a complete stop. Is this an elastic collision (i.e. is kinetic energy conserved)? Show your work.

You, the driver of the 25 kg hovercraft, are upset and decide to retaliate by bumping the Troy 35 kg hovercraft. The Troy hovercraft is travelling at 3 m/s towards your 25 kg hovercraft, and you drive your 25 kg hovercraft at 5.0 m/s head-on into the Troy hovercraft. If after the collision, the resultant velocity of your 25 kg hovercraft is v = 4.33 m/s what is the resultant velocity of the Troy 35 kg hovercraft? Assume this collision is elastic (both momentum and kinetic energy are conserved). Show your work.

A cube with side length l = 0.50 m displaces 0.10 m³ of water (ρ = 1000 kg/m³) when dropped in a large pool. What is the density of the cube? Show your work.

Which of the following must be true for the basic Bernoulli's equation to apply?

A fluid of constant density flows steadily, left to right, in the pipe below. How does the fluid's velocity (v₁, v₂) and pressure (p₁, p₂) compare at each point?

100 milliliters of water is poured into a U-tube that has a cross-sectional area of 1.0 cm². Then 100 milliliters of oil, with a density 80% that of water, is poured down one side of the U-tube so that the oil floats on the water. Find the difference in height of the liquid surfaces on the two sides of the U-tube. Show your work.

You are still mad at your hovercraft. After throwing it off the roof of the parking garage, you decide to throw it into the pool. As your hovercraft sinks deeper and deeper into the water of the pool, and the water is of constant density, what happens to the buoyant force on your hovercraft?

A fountain sends a stream of water 20 m up into the air. If the base of the stream is 10 cm in diameter, what power is required to send the water to this height? Show your work.

Determine the minimum area of a flat ice floe 1.0 meter thick if it is to support a 2000 kg car above seawater. (ρ_ice = 920 kg/m³, ρ_sea = 1020 kg/m³.) Show your work.