A 2.0 kg mass is lifted 4.0 m above the ground. find the change in gravitational energy
1 answer:
Answer:
78.4 J
Explanation:
Given:
Mass of the object (m) = 2.0 kg
Height or displacement of the mass (h) = 4.0 m
Now, change in gravitational potential energy (ΔU) = ?
Change in gravitational potential energy of an object is the energy stored by the object when it is raised to some height above the reference ground level.
Change in gravitational potential energy of an object of mass 'm' raised to a height 'h' above the ground is given as:
Where, 'g' is the acceleration due to gravity and has a value of 9.8 m/s².
Now, plug in all the given values and solve for ΔU. This gives,
Therefore, the change in gravitational potential energy is 78.4 J.
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Answer:
A line crossing the x-axis in a velocity-time graph means that the moving object has changed its direction.
Explanation:
Velocity-Time graph:
A velocity-time graph is a two dimensional graph with velocity at its y-axis and time at its x-axis. At any point, value of y represents the velocity and value of x represents the time. The slope of the graph gives us the acceleration or deceleration of the moving object.
In a velocity-time graph:
- A straight line represents constant velocity.
- A diagonal line means that the velocity of a body is changing.
*Referring to the figure attached with the answer*
The velocity of the moving object increases at a constant rate for the first 10 minutes. Then the velocity is 60 m/min for the next 5 minutes. After that the velocity is decreasing. Till 30th minute when the velocity is at 0 m/min.
What happens here?
Velocity is a vector quantity. It has some direction. In a velocity-time graph, we are only concerned with two directions of velocity:
- Forward direction
- Backward direction
So, the object stops at 30th minute and starts moving in the reverse direction after that with an increasing velocity. <u>The point where the line cuts the x-axis is basically the point where the object starts moving in the reverse direction.</u>
Answer:
= 922N
Explanation:
m = 64kg
v(t) = (3.0 m/s²)t + (0.20 m/s³)t².
t = 4.0s
differentiation of v(t) so the acceleration is given by
using Newton’s second law
F (net) = ΣFg = ma
⇒R - w = ma
R = m(a + g)
= 64 (9.81 + 4.6)
= 922N