10th U1 Friction Forces

How much is the mass?

• 5 kg

• 5 x 10 = 50 kg

• 10 kg

• 5 x 10 = 50N

What is weight?

• Forced pulled by the planet to its center

• Forced pulled by the planet to its space

• Forced pushed by the planet to its center

• Forced pushed by the planet to its space

What is the weight of this mass?

• W = (5kg)(10m/s²) = 50N

• W = (5kg)(10) = 50Kg

• W = (5)(10) = 15N

• W = (5)(10) = 15kg

What does the vertical red arrow indicate?

• Weight

• Normal force

• Applied Force (F_app)

• Friction Force

What does the Blue arrow indicate?

• Weight

• Normal force (also known as Reaction, R)

• Applied Force (F_app)

• Friction Force

How much is the Normal Force?

• N = weight = 5kg

• N = weight = 50N

• N = mass = 5kg

If Ff_s =μ _s•N and

μ_s=0.6 and μ_d=0.4

Find the maximum static force of friction.

• (0.6)(50) = 30N

• (0.6)(50) = 30kg

• (0.4)(50N) = 20N

• (0.4)(50N) = 20kg

If Ff_s = μ_s•N and

μ_s=0.6 and μ_d=0.4

Find the dynamic force of friction.

• (0.6)(50) = 30N

• (0.6)(50) = 30kg

• (0.4)(50N) = 20N

• (0.4)(50N) = 20kg

If μ_s=0.6 and μ_d=0.4

Is it moving if we apply 25N?

• No, because is less than 0.6*50N=30N

• No, because is less than 5kg

• Yes, because is less than 0.6*50N=30N

• Yes, because is more than 5kg

If μ_s=0.6 and μ_d=0.4

If we apply 25N, what is the type of friction experiencing?

• Static, 25N is less than 0.6*50N

• Dynamic, 25N is less than 0.6*50N

• Static, 25N is less than 5kg

• Dynamic, 25N is less than 5kg