Question

This and the following question relate to the same situation:

A raft is 4.2 m wide and 6.5 m long and it floats on water (density of water = 1000 kg/m³). When a horse is loaded onto the raft, it sinks an additional 0.027 m deeper into the water. What is the weight of the horse?

(a)   7200 N
(b)   1400 N
(c)   2400 N
(d)   9500 N
(e)   5700 N

QUESTION 16*

What if the same horse were put on the same raft floating in salt water, which is more dense than fresh water. The raft sinks an additional amount which is

(a)   less than 0.027 m.
(b)   equal to 0.027 m.
(c)   greater than 0.027 m.

QUESTION 17**

A hot air balloon plus its cargo has a mass of 327 kg and a volume of 687 m³. The balloon is floating at a constant height above the ground. Given that the density of the surrounding air is 1.27 kg/m³, what is the density of the hot air inside the balloon?

(a)   0.25 kg/m³
(b)   0.45 kg/m³
(c)   0.62 kg/m³
(d)   0.79 kg/m³
(e)   1.36 kg/m³

QUESTION 18*

As a storm approaches, you notice that the column of mercury (density = 13,600 kg/m³) rises only to a height of 740 mm. What is the air pressure?

(a)   0.85

Answer 1

15. weight of water displaced = weight of horse
4.2 x 6.5 x 0.027 x 1000 x 9.8= weight of horse
= 7200 N (approx)
16. density of salt water is greater than fresh water, hence
The raft sinks an additional amount which is
(a)   less than 0.027 m.

17. let density of hot air be d
(327+687 x d ) x 9.8 = 1.27 x 687
d = 0.346kg/m^3

18.
air pressure = density x 9.8 x.74 m = 0.99 x 10^5 Pa