A uniform meter rule of mass 10g is balanced on a knife edge placed at 45cm mark. Calculate the distance of a mass 25g from the pivot

2 cm.

Explanation:

Please see attached photo for diagram.

In the attached photo, y is the distance from the pivot to which the 25 g is placed.

The value of y can be obtained as follow:

Clockwise moment = 5 × 10

Anticlock wise moment = y × 25

Anticlock wise moment = Clockwise moment

y × 25 = 5 × 10

y × 25 = 50

Divide both side by 25

y = 50/25

y = 2 cm

Thus, the distance is 2 cm

a) 3 m/s b) 1362 N c) 1.5 m/s

Explanation:

Using conversation law of momentum

M₁U₁ + M₂U₂ = M₁ V₁ + M₂V₂ where M₁ =3m, M₂ = m, time of impact t = 1 ms = 1 / 1000 in s = 0.001 s

substitute the values

a) 3m × 2 + 0 = 3m × 1 + m × V₁

6 = 3 + V₁

V₁ = 3 m/s

b) force of impact = ma = m × Δv / t = (0.454 × 3 ) / 0.001 = 1362 N where m = 0.454 kg

c) 3m× 2 + 0 = V (3m + m)

6m = 4mV

V = 6m / 4m = 1.50 m/s