FBD Practice

1. Book at rest on table

FN

Fg

ΣFy = may

FN – Fg = 0

2. Girl holding rope

T

Fg

ΣFy = may

T – Fg = 0

3. Free Falling Egg

Fg

ΣFy = may

– Fg = may

4. Book accelerating to right

FN

Fg

FAf

ΣFy = may

FN – Fg = 0

ΣFx = max FA – f = max

5. Book across desk at constant v

FN

Fg

FAf

ΣFy = may

FN – Fg = 0

ΣFx = max FA – f = max FA – f = 0

6. Sled with acceleration left

FN

Fg

fFA

ΣFy = may

FN – Fg = 0

ΣFx = max f - FA = max

7. Football near peak of flight

Fg

ΣFy = may

– Fg = may

8. Car coasting right but slowing down

FN

Fg

f

ΣFy = may

FN – Fg = 0

ΣFx = max – f = max

9. Shopping cart with 40° push down and to right moving at constant speed

FN

FgFA

f40 °

ΣFy = may

FN – Fg – FAsin40 = 0

ΣFx = max FAcos40 – f = max

FAcos40 – f = 0

10. Sled accelerated left by pull at 30° above horizontal

FN

Fg

FA

30 °

ΣFy = may

FN – Fg + FAsin30 = 0

ΣFx = max -FAcos30 = max

Try it…

• 1. A shuffleboard puck slowing to a stop as it slides across the court

• 2. A crate pulled at a constant speed to the left by a rope that makes a 25 degree angle with the horizontal