Answer: 6.21 m/s opposite to Janet
Explanation:
Given
mass of Janet ![m_j=59\ kg](https://tex.z-dn.net/?f=m_j%3D59%5C%20kg)
mass of Sarah ![m_s=32\ kg](https://tex.z-dn.net/?f=m_s%3D32%5C%20kg)
The initial velocity of Janet
The final velocity of Janet after the collision is ![v_1=2\ m/s](https://tex.z-dn.net/?f=v_1%3D2%5C%20m%2Fs)
the final velocity of Sarah after the collision is ![v_2=3\ m/s](https://tex.z-dn.net/?f=v_2%3D3%5C%20m%2Fs)
Conserving linear momentum
![\Rightarrow m_ju_1+m_su_2=m_jv_1+m_sv_2\\\Rightarrow 59\times 7+32\times u_2=59\times 2+32\times 3\\\Rightarrow 32u_2=118+96-413\\\Rightarrow u_2=\frac{-199}{32}=-6.21\ m/s](https://tex.z-dn.net/?f=%5CRightarrow%20m_ju_1%2Bm_su_2%3Dm_jv_1%2Bm_sv_2%5C%5C%5CRightarrow%2059%5Ctimes%207%2B32%5Ctimes%20u_2%3D59%5Ctimes%202%2B32%5Ctimes%203%5C%5C%5CRightarrow%2032u_2%3D118%2B96-413%5C%5C%5CRightarrow%20u_2%3D%5Cfrac%7B-199%7D%7B32%7D%3D-6.21%5C%20m%2Fs)
Negative indicates the direction of velocity is opposite than of Janet
Answer:
S = V t - 1/2 a t^2 a here is negative due to deceleration
S = 4 * 8 - 1/2 * 64 = 0
The object just returns to its original starting point
It started out at 8 m/s which was reduced to 0 m/s after 4 sec
In 4 more seconds it was moving at -8 m/s, just the opposite of where it started
Answer:
a) It will take you 16.94 min to climb the stairs.
b) The numbers of flights are 123 flights.
Explanation:
a) Let the energy consumption while climbing the stairs be 685 W in kcal/min is given by:
rate of energy consumption = (685 W)×[(0.01433kcal/min)/1 W]
= 9.81605 kcal/min
the time it takes to climb the stairs is given by:
t = E/P
= (166.0 kcal)/(9.8 kcal/min)
= 16.94 min
Therefore, it will take you 16.94 min to climb the stairs.
b) Given t is the time it takes to climb stairs and N is the number of stairs to climb per min, then the number of stairs is:
n = t×N
= (16.94)×(116)
= 1965 stairs
given the number of stairs each flight as N1, then the number of flights is given by:
flights = n/N1
= (1965)/(16)
= 123 flights
Therefore, the numbers of flights are 123 flights.