Quiz 2b (Phys 101 - 11.30am, Spring 2005)


Name: __________________Answers____________________


  1. You are driving a convertible car (with it`s top down) at a constant velocity of 30km/hour. A passenger in the car throws a rock vertically in the air. Where will the rock land?

a)   On top of the passenger (this is because both the rock and car have the same horizontal velocity)

b)       In front of the car

c)       Behind the car

d)       Indeterminate as it depends upon how hard the passenger throws the rock.



  1. An astronaut has a weight of 500N on Earth.

a)       What is his mass on Earth?

m = W/g = 500/10 = 50kg

b)       What is his mass in space?

m = 50kg (i.e. it is unchanged in space)


  1. A parachutist of mass 100kg jumps out of a plane. A force due to air resistance of 400N slows down his decent.

a)       What is the net force acting on the parachutist?

F(net) = W F(air resistance) = 100x10 400 = 600N, down

b)       What is the parachutist`s acceleration?

a = F(net)/m = 600/100 = 6m/s2, down