A.2 Forces (old curriculum)

What is the Normal Force?

• 10•9.81 – 20

• 10•9.81 + 20

• 10•9.81

• 20•9.81

If μ_s = 0.6 and μ_d = 0.4

Ignore force = -65N

What is the maximum friction to overcome and start moving the block?

• = 0.6 • (10•9.81 – 20)

• = 0.6 • (10•9.81 + 20)

• = 0.4 • (10•9.81 – 20)

• = 0.4 • (10•9.81 + 20)

If μ_s = 0.6 and μ_d = 0.4

Ignore force = -65N

What is the friction while the object is sliding?

• = 0.6 • (10•9.81 – 20)

• = 0.6 • (10•9.81 + 20)

• = 0.4 • (10•9.81 – 20)

• = 0.4 • (10•9.81 + 20)

Ignore friction.

What is the force needed to have translational equilibrium to this block?

• exactly 65 N to the right

• exactly 65 N to the left

• more than 65 N to the right

• more than 65 N to the left

If μ_s = 0.6 and μ_d = 0.4

How can we find acceleration?

• = ∑F / m

• = ∑F • m

• = m / ∑F

• = m + ∑F

If μ_s = 0.6 and μ_d = 0.4 and object is moving ...

How can we find acceleration?

• = [0.4 • R – 65] / 10kg

• = [0.6 • R – 65] / 10kg

• = [0.4 • R – 65]

• = [0.6 • R – 65]

If μ_s = 0.6 and μ_d = 0.4

Is the force 65N enough to start moving it?

• Yes, 65 > 0.6 ( mg - 20)

• Yes, 65 > 0.6 ( mg)

• No, 65 > 0.6 ( mg - 20)

• No, 65 > 0.6 ( mg )

What is the reaction force?

• 10,000 N upwards

• 1,000 N upwards

• 10,000 kg upwards

• 1,000 kg upwards

What is needed to accomplish 1st Newton's Law

• 10,000 N to the left

• 10,000 N upwards

• 10,000 N downwards

• 10,000 N to the right

What is needed to have negative acceleration while car is moving to the right?

• Opposite forces > thrust.

• Opposite forces < thrust.

• Opposite forces = thrust.