1. Simple applications
Of 1st & 2nd Laws

2. Applications of Newton’s Laws
vo= 20 m/s
m = 5 kg
v = 0 F m d
Find distance
block moves

3. inside a stationary elevator.
A man stands on a scale
inside a stationary elevator.
Forces acting on the man N
Reading
on scale mg
Dynamics: Newton’s Laws of Motion

4. When Moving Upward With Constant Velocity
Forces acting on the man v N mg
Reading
on scale
Dynamics: Newton’s Laws of Motion

5. When Moving Upward With Constant Acceleration
Forces acting on the man a N mg
Reading
on scale
Dynamics: Newton’s Laws of Motion

6. When Moving Downward With Constant Acceleration
Forces acting on the man a N mg
Reading
on scale
Dynamics: Newton’s Laws of Motion

7. Determine the magnitude of the forces acting on each of the 2 kg masses at rest below.
30°
30°
30°
60°

8. ∑Fx = 0 and ∑Fy = 0
mg = 20 N
N = 20 N

9. ∑Fx = 0 and ∑Fy = 0
T1 = 10 N
20 N
T2 = 10 N

10. 30°
mg = 20 N
T1 = 20 N
T2 = 20 N
Method 1: ∑Fx = 0 and ∑Fy = 0
Method 2: ∑F = 0

11. ∑Fx = 0 and ∑Fy = 0 Method 1: ∑Fx = 0 and ∑Fy = 0 Method 2: ∑F = 0 30°
T1 = 40 N
T2 = 35 N
Method 1: ∑Fx = 0 and ∑Fy = 0
Method 2: ∑F = 0

12. A Harder Problem! a. Which string has the greater tension?
b. What is the tension in each string?
30°
60°

13. Applications of Newton’s Laws
Find Tensions T1 and T2 q
T1 sin(60)
T1 cos(60) T1 T2 mg m
q = 60o
m = 20 kg

14. Applications of Newton’s Laws
Another method q T1 q mg T1 T2 T2 mg m

15. Applications of Newton’s Laws
Three mass system - find acceleration F m 2m 3m
Find the tensions in the string.
First find the acceleration of the system.
Laws of Motion (Chapter 4) 2053.ppt

16. T2 F m 2m 3m Three mass system - find T2
Laws of Motion (Chapter 4) 2053.ppt

17. T1 T2 F m 2m 3m Three mass system - find T1
Laws of Motion (Chapter 4) 2053.ppt

18. If Hand force is 150N Find the acceleration of the system
With what force does the 5kg block push on the 10 kg block?