F = net force acting on the elevator in upward direction = 3000 N
m = mass of the elevator = 1200 kg
a = acceleration of the elevator = ?
Acceleration of the elevator is given as
a = F/m
a = 3000/1200
a = 2.5 m/s²
v₀ = initial velocity of the elevator = 0 m/s
Y = displacement of the elevator = 15 m
t = time taken
Using the kinematics equation
Y = v₀ t + (0.5) a t²
15 = (0) t + (0.5) (2.5) t²
t = 3.5 sec
Answer:
increase.
Explanation:
According to the newton’s second law of motion force is expressed as product of mass and acceleration.
F = m a
If the force acting is constant, then.
m∝ 
That is if the mass of object increases the acceleration decreases and vice versa. The above equation is used when the force acting on the body is constant.
As the thrust force from the rocket engine is constant throughout there will be a variation in the mass or acceleration.
Thus, it won't stay the same.
As the weight of the car is maximum at the start because of the fuel present in the rocket engine and minimum at the end as the fuel burns throughout the journey of the car. Weight will be minimum at the end and hence acceleration is maximum at the end.
Thus, it won't decrease.
As the acceleration is going from minimum at the start to maximum at the end, therefore it is continuously increases throughout its journey.
Thus, it will increase.
Internal and external combustion engines are two types of heat engines: they convert thermal energy into mechanical energy. The main difference between internal and external combustion engine is that in internal combustion engines, the working fluid burns inside the cylinder, whereas in external combustion engines, combustion takes place outside the cylinder and heat is then transferred to the working fluid.