Mass Of Car Write Up (recent)

Ryan Thomas A.P. Physics 10/8/07 Mass of the Car Write Up Purpose: To determine the mass in kilograms and the rolling friction force of a car. Equipment: •1997 Honda Civic •Tape Measure •Marker Cones

•2 Bathroom Scales •Stop Watch

Assumptions: The main assumption made in the calculations is that air resistance does not act on the car during the experiment; this serves to simplify calculations, and will not significantly alter results, as the force of air resistance here is minimal. Other assumptions are that the figures collected are accurate and that they are precise; also, the force on the car is assumed constant. Calculations: •Known Information: The car begins moving from an inert state as 40 lbs of force are exerted upon it; therefore, this is the force of static friction upon the car (See Fig. 1). With a constant 100 lbs of force upon it, the car moves 20.5 m in 30 sec (See Fig. 2). •Problem: Find the mass of the car and the force of rolling friction on the car. Step 1 – Calculate the mass of the car υ = d/t = 20.5m/30s; 0.683m/s = υ; 2 υ = υf = 1.37m/s; a = Δυ/Δt = 1.37m/s/30s = 0.0455m/s2; ΣF = ma; ΣF = FR – FF(static) = 100 # - 40 # = 60 #; 60 # * 4.45 N / # = 267 N 267 N = 0.0455 m/s2 * m; 5868.13kg = m Step 2 – Calculate the force of rolling friction on the car 100 # - Ff(rolling) = ma; 445 N – 267 N = Ff(rolling) = 178 N

Sources of Error: The main source of error in the experiment is the uncertainty of proper cone placement; for example, if each cone were placed just a slight bit off the mark, it would significantly alter results as far as distance is concerned. Also, since procedure and accuracy in data collection varied between groups, the results of the different groups are not necessarily the same. The above calculations show that the car’s mass is approximately 5868 kg, and the force of rolling friction that acts upon it has a magnitude of about 178 N.