Answer:
32.5 m/s
Explanation:
The total momentum must be conserved before and after the collision:
where
m_c = 300 kg is the mass of the car
m_t = 600 kg is the mass of the truck
u_c = 60 m/s is the initial velocity of the car
u_t = 10 m/s is the initial velocity of the truck
v_c = 15 m/s is the final velocity of the car
v_f is the final velocity of the truck
Solving for v_f, we find:
Answer:
Answer C : person on an elevator going down
Explanation:
We look for a change in state of motion in order to have a net force different from zero in the system. The state of motion doesn't change in any of the examples a, b, or d. But there is a change in the state of motion in case c where initially the person and elevator where in static equilibrium, and later the elevator started going down and accelerating from zero speed to another non zero speed.
Answer:
Work done, W = 6 J
Explanation:
It is given that,
Force of gravity acting on the book, weight of the book is 15 N
We need to find the work done in lifting the book straight up for a distance of 0.4 meters.
The weight of the book is acting in downward direction and the book is lifted straight up, it means angle between them is 180 degrees. Work done is given by :
So, the magnitude of work done in lifting the book is 6 joules.