The document contains two physics problems asking about the tension in a string suspending a submerged sphere and the time taken for a box to move 4 meters from rest with a constant horizontal force applied. The solution finds that the tension in the string suspending the submerged sphere is 34.5 N. For the box problem, it calculates that with a net force of 27.5 N and the box mass of 25 kg, the time taken to move 4 meters is approximately 2.7 seconds.

1. help me answer these two questions
14. A 4.7 kg solid sphere, made of metal whose density is 4000 kg/m3, is suspended by a string
in water. The density of water is 1000 kg/m3. What is the tension in the string when the sphere is
completely immersed? a) 10.6Nby 34.5 N 44.9N d) 46.1N e) 57.6 N 15. A 25 kg box is being
pushed across a level floor by a constant horizontal force of 150 N. If the coefficient of kinetic
friction between the box and the floor is 0.50, how long does it take the box to move 4.00 m,
starting from rest? 0.54 s b) 0.86 s 1.2sd)1.35e)2.7s
Solution
A) The actual weight of the sphere is
mg = 4.7 * 9.8 = 46.06 Newtons
Since water has only one quarter the density of the metal, the buoyant force is one quarter the
weight of the sphere, or 46.06 / 4 = 11.515Newtons
Since the water pushes up with this force, the cord only hasto support the remainder of the
weight of the sphere,or
46.06 - 11.515 = 34.5 Newtons
So the tension in the cord is 34.5 N
B)
Fnet = F = friction
Fnet = 150 - uN = 15-25*9.8*0.5 = 27.5 N
Fnet = ma = 27.5
a = 27.5/m = 27.5/25 = 1.1 m/s^2
s = ut + 1/2*at^2

2. 4 = 0 + 0.5*1.1t^2
t = sqrt(4*2/1.1) = 2.6968 seconds ~ 2.7 seconds