JAMB - Physics (1981 - No. 21)
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?
the car will be able to stop immediately the driver notices the dog
the car will stop 30m after hitting the dog
the car will stop 20m in front of the dog
the driver will quickly reverse the car
the car will stop 5m beyound the dog
설명
F=ma
2000=800 x a
a = \(\frac{2000}{800}\) → 2.5
V\(^2\)=u\(^2\)+2as
400=2 × 2.5 × S
S =400 ÷ 5 → 80
: 80 - 50 = 30
The car will stop 30m after hitting the dog
2000=800 x a
a = \(\frac{2000}{800}\) → 2.5
V\(^2\)=u\(^2\)+2as
400=2 × 2.5 × S
S =400 ÷ 5 → 80
: 80 - 50 = 30
The car will stop 30m after hitting the dog