Answer:
3.80 m/s
Explanation:
Solution: From the question we have:
A 2.10 x 10^3 kg car starts from rest at the top of a 5.0 m long driveway that is sloped at 20 degrees with the horizontal.
average friction force of 4.0 x 10^3 N impedes the motion
To find out: find the speed of the car at the bottom of the driveway.
=>h = 5×sin20 = 1.71 m.
PE = mgh = 2100×9.8×1.71 = 35,192 J.
KE = PE-work done by frictional force
KE=PE-4000×5
0.5mV^2 = 35192 - 4000×5
1050V^2 = 15,192
V^2 = 14.47
V = 3.80 m/s.
Answer:
37.7m/s: principle of conservation of momentum
Explanation:
The principle to make use of is the principle of conservation of momentum which States that the sum of momentum of bodies before collision is equal to the sum of momentum of bodies after collision. This bodies will move with the same velocity after collision.
Momentum = Mass × velocity
For car of mass 2200kg moving with velocity 33m/s:
Momentum of car before collision = 2200×33
= 72,600kgm/s
For the truck of mass 4500kg;
Momentum = 4500 ×(22-(-18)
= 4500×40
= 180000kgm/s
After collision, their momentum is:
Momentum after collision = (2200+4500)v
= 6700v
Using the principle above to get the common velocity v we have
72600+180000 = 6700v
252600 = 6700v
v = 252600/6700
v = 37.7m/s
