sledge of mass 80 kg moves over the frozen surface of a lake with a velocity of 30m/s and comes to rest in 5s. find frictional force between the lake and sledge
Average acceleration
=(0-30) m/s ÷ 5 s
= -6 m/s²
Force
= ma = 80 kg * (-6 m/s²)
= -480 N (resistive force)
F=ma
F=80×-30/5
F=80×6=-480N
Declaration=change in velocity
/time -30/5=-6mssquare
To find the frictional force between the lake and the sledge, we can use Newton's second law of motion, which states that the net force acting on an object is equal to the product of its mass and acceleration. In this case, we need to find the acceleration of the sledge when it comes to rest.
Given:
Mass of the sledge (m) = 80 kg
Initial velocity (u) = 30 m/s
Final velocity (v) = 0 m/s
Time taken (t) = 5 s
Using the equation:
v = u + at
where:
v = final velocity
u = initial velocity
a = acceleration
t = time taken
Rearranging the equation to solve for acceleration (a):
a = (v - u) / t
Substituting the given values:
a = (0 - 30) m/s / 5 s
a = -6 m/s^2
The negative sign indicates that the acceleration is opposite to the direction of motion.
Now, we can find the frictional force (F) using Newton's second law:
F = m * a
Substituting the given values:
F = 80 kg * -6 m/s^2
F = -480 N
The negative sign indicates that the frictional force is acting in the opposite direction of the motion of the sledge. Therefore, the frictional force between the lake and the sledge is 480 N.
To find the frictional force between the lake and the sledge, we can use Newton's second law of motion, which states that the net force acting on an object is equal to the product of its mass and acceleration:
Net force = mass × acceleration
In this case, the net force is the frictional force acting on the sledge, and the acceleration is the change in velocity divided by the time taken to come to a stop.
Given:
Mass of the sledge (m) = 80 kg
Initial velocity (u) = 30 m/s
Final velocity (v) = 0 m/s
Time taken (t) = 5 s
First, we need to calculate the acceleration:
Acceleration (a) = (v - u) / t = (0 - 30) m/s / 5 s = -6 m/s^2
The negative sign indicates that the velocity is decreasing.
Now, we can calculate the frictional force using Newton's second law:
Frictional force (F) = mass × acceleration = 80 kg × (-6 m/s^2) = -480 N
The negative sign indicates that the frictional force acts in the opposite direction to the motion of the sledge.
Therefore, the magnitude of the frictional force between the lake and the sledge is 480 N.