In: Physics
3.) To maintain a constant speed, the force provided by a car's engine must equal the drag force plus the force of friction of the road (the rolling resistance). Assume all values are accurate to three significant digits. (Assume the density of air is 1.21 kg/m3.)
A.) What is the magnitude of drag force (in N) at 58 km/h and 116 km/h for a Toyota Camry? (Drag area is 0.70 m2, and drag coefficient is 0.28.)
B.) What is the magnitude of drag force (in N) at 58 km/h and 116 km/h for a Hummer H2? (Drag area is 2.44 m2, and drag coefficient is 0.64.)
PART A:
The drag force is given by
Where,
is the density of the fluid. In our case 1.21 kg/m3.
is relative velocity
is drag coefficient and
is the cross-sectional area.
Now putting the values for 58 km/h
So, for Toyota Camry, drag force at 58 km/h is 30.77 N.
Now putting the values for 116 km/h
So, for Toyota Camry, drag force at 116 km/h is 30.77 N.
PART B:
Putting the values for 58 km/h
So, for Hummer H2, drag force at 58 km/h is 245.2 N.
Now putting the values for 116 km/h
So, for Hummer H2, drag force at 116 km/h is 980.79 N.