The driver in a motor car, of which the total mass is 800kg and which is traveling at 20ms-1, suddenly observes a stationary dog in his path 50m ahead. If the car brakes can exert a force of 2000N, what will most likely happen?
A
the car will be able to stop immediately the driver notices the dog
B
the car will stop 30m after hitting the dog
C
the car will stop 20m in front of the dog
D
the driver will quickly reverse the car
E
the car will stop 5m beyound the dog
Verified Correct Answer: B.
Physical Principles & Numerical Solution
F=ma
2000=800 x a
a = \(\frac{2000}{800}\) → 2.5
V\(^2\)=u\(^2\)+2as
400=2 \times 2.5 \times S
S =400 \div 5 → 80
: 80 - 50 = 30
The car will stop 30m after hitting the dog
Source: WAEC / JAMB / NECO Classroom Archive (Record #29010)