P5 - Space for Reflection

Satellites

• Why are geostaionary satellites placed in an orbit that takes 24 hours?
• Compare the force on a satellite 40,000Km above the Earth with one 80,000Km above the earth.
• Compare the height of a polar orbit satellite to the height of a geostationary satellite.
• Show what the approximate speed of a low polar obrit is 7.5Km/s. Assume radius of Earth is 6400Km.

Vectors

• Which of these are scalar quantities:Mass, temperature, force, acceleration and volume?
• What is the resultant of two perpendicular forces of 9N and 12N?
• A renault Espace accelerates from 0-30M/s in 3s. How far does the car travel in that time ?

Projectile motion

• Heaver serces at tennis, striking the ball horizontally. What is the horizontal acceleration of the ball as it crossed the court to her opponent?
• As heather serves, the tennis ball is 2.45m above the ground. The serve beats her opponent, how long is the ball in the air before it hits the ground?
• A golf ball has a mass of 45.9g. Calculate the force acting on it when its in flight.

Momentum

• Calculate the momentum of a 0.15Kg cricket ball travelling at 30M/s.
• Calculate the force on a 55Kg pssenger if a seat belt takes 0.75s to bring her to rest from an intial velocity of 18M/s.
• When a parachutist lands, he bends his legs. Explain why.