A car traveled 60km in 45 min.What is the cars average speed in km/hr
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An elevator has 750,000 J when it is lived 500 meters in the air
Answer: Option D
<u>Explanation:</u>
The expression to find the potential energy completely on the basis of forces that on two objects. It can be written as
Where,
m – mass of object
Acceleration due to gravity =
h = 500 meters
Force = 1500 Newton
As we know, according to Newton second law of motion, the force can be expressed in terms of mass and gravity (F= ma). So, the potential energy can be calculated as
Hence, an elevator has 750,000 J when it is lived 500 meters in the air.
Answer:
d) None of the above
Explanation:
= inituial velocity of launch = 4 m/s
θ = angle of launch = 10 deg
Consider the motion along the vertical direction
= initial velocity along vertical direction = 4 Sin10 = 0.695
m/s
= acceleration along the vertical direction = - 9.8 m/s²
y = vertical displacement = - 20 m
t = time of travel
using the equation
- 20 = (0.695) t + (0.5) (- 9.8) t²
t = 2.1 sec
consider the motion along the horizontal direction
x = horizontal displacement
= initial velocity along horizontal direction = 4 Cos10 = 3.94 m/s
= acceleration along the horizontal direction = 0 m/s²
t = time of travel = 2.1 s
Using the kinematics equation
x = (3.94) (2.1) + (0.5) (0) (2.1)²
x = 8.3 m
Consider the motion along the vertical direction
= initial velocity along vertical direction = 4 Sin10 = 0.695
m/s
= acceleration along the vertical direction = - 9.8 m/s²
=initial vertical position at the time of launch = 20 m
= vertical position at the maximum height = 20 m
= final velocity along vertical direction at highest point = 0 m/s
using the equation
= 20.02 m
h = height above the starting height
h = -
h = 20.02 - 20
h = 0.02 m