Question

1.Four forces act on a 1000 kg car in a concrete parking lot on University:

9800 N of weight force downward  ↓
9800 N of concrete’s rigidity force upward  ↑
100 N of you pushing the car north  →
80 N of friction pushing south against you.  ←

(Make your own sketch.)

What is the net force on this car?

a.9980 N, northward →

b.20 N, northward →

c.9620 N, upward  ↑

d.180 N, downward  ↓

2.A Nissan Altima moves north on Alafaya at constant speed 45 mph. Therefore you could say that

a.there are no forces acting on the Altima.

b.there are forces acting on the Altima, but they all balance out.

c.it has velocity but not a direction.

d.it is accelerating.

Answer 1

1.

Along vertical direction

Net force=9800-9800=0 N

Along hirezontal direction

Net force = 100-80

= 20 N

Therefore correct option is (b)

2.

In this condition, there are force acting on Altima (gravitational force, contact force, friction force, forward push force)

But all the forces are balanced out

Velocity of Altima has direction i.e. northward

Since Altima is moving at constant speed so acceleration is '0'

So correct option is (b)