Answer to Question #266753 in Physics for Frizie

Question

7. Find the specific gravity, weight density, and volume of the unknown object if it

weighs 40 Ib in air and 30 Ib in water.

2. A 10,000 kg vehicle will round the having a radius of 150 meter. The curved road is

banked at 25 degrees with the horizontal, find the minimum coefficient of friction.

4. Find the acceleration and the centripetal force of a 14 kN car that rounds the curved

of radius of 50 meters having a speed of 8 km/h.

5. Two perfectly elastic balls, weighing 27 N and 18 N, approach each other with a

speed of 6 m/s and 11 m/s, respectively. What is the speed of the balls after the

collision?

Answer 1

7. $40\ lb=178\ N$ ; $30\ lb=133\ N$

Specific gravity $SG=\rho_{object}/\rho_{water}=178/133=1.34$

Density $\rho=1.34\cdot1000=1340\ (kg/m^3)$

$V=178/(1340\cdot9.8)=0.014\ (m^3)$

2. Suppose that $v=5\ (m/s)$ . So, we have

$\mu=\frac{-v^2\cos25°+gR\sin25°}{v^2\sin25°+gR\cos25°}=\frac{-5^2\cdot\cos25°+9.8\cdot 150\cdot\sin25°}{5^2\cdot\sin25°+9.8\cdot150\cdot \cos25°}=0.45$

4. $a=v^2/r=2.22^2/50\approx0.1\ (m/s^2)$ and $F=ma=(14000/9.8)\cdot0.1=141\ (N)$

5. $v_1=\frac{m_1-m_2}{m_1+m_2}u_1+\frac{2m_2}{m_1+m_2}u_2=\frac{2.8-1.8}{2.8+1.8}\cdot 6+\frac{2\cdot 1.8}{2.8+1.8}\cdot 11=$

$=9.91\ (m/s)$

$v_2=\frac{2m_1}{m_1+m_2}u_1+\frac{m_2-m_1}{m_1+m_2}u_2=\frac{2\cdot 2.8}{2.8+1.8}\cdot 6+\frac{1.8-2.8}{2.8+1.8}\cdot 11=$

$=4.91\ (m/s)$