Question

1. A 0.020 kg and a 0.060 kg ball are at the two opposite ends of a compressed spring. When the spring expands, the 0.060 kg ball is shot at a speed of 3 m/s. Assuming no energy loss, calculate the shot speed of the other ball.

A.9 m/s

B.6 m/s

C.3 m/s

D.1 m/s

2. Calculate the gravity force between the Earth and the Sun.

m_sun = 1.99×10³⁰ kg ; m_Earth = 5.97×10²⁴ kg ; Earth-Sun distance : 1.50×10¹¹ m ;

G = 6.67×10^-11 Nm²/kg²

A.3.52×10²² N

B.6.41×10^-14 N

C.3.52×10⁴⁴ N

D.5.28×10³³ N

3.Weigh the Moon. From the value of the gravity acceleration (free fall acceleration) g_Moon = 1.62 m/s² and its radius R_Moon = 1.74 × 10⁶ m, calculate the mass of the Moon. (G = 6.67×10^-11 Nm²/kg²)

A. 7.35 kg

B. 4.22 × 10¹⁶ kg

C. 6.52 × 10³³ kg

D. 7.35 × 10²² kg

4. If the Earth were made by the same materials but its radius were twice as much, then its mass would be eight times bigger. How would the surface gravity acceleration (or free fall acceleration) be in that case?

A. Four times bigger

B. Twice bigger

C. Twice smaller

D. The same

Answer 1