While you are in a bus that moves at 100 km/h you walk from the back to the front at 10 km/h. What is your speed relative to the
1 answer:
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Answer:
(a) The ball lands <u>1 m</u> ahead of the desk's base.
(b) The height of the desk is <u>1.225 m.</u>
Explanation:
Given:
Initial velocity of the ball is,
Time of flight of the ball is,
(a)
Let the ball fall at a distance of from the base of the desk and let the height of the desk be
.
The given motion of the ball is a projectile motion that can be divided into 2 mutually perpendicular directions.
Now, considering only the horizontal motion of the ball. The ball not under the influence of any force in the horizontal direction.
Therefore, the distance covered by the ball horizontally is given as:
So, the ball lands 1 m ahead of the desk's base.
(b)
Now, consider only the vertical motion of the ball. The ball is under the influence of gravity.
So, vertical distance can be obtained using Newton's equations of motion.
We use the following equation of motion:
Where,
Here, as the ball leaves the desk horizontally, initial velocity is only in the horizontal direction and doesn't have any component in the vertical direction. So,
Plug in . Solve for
.
Therefore, the height of the desk is 1.225 m.
Answer:
The velocity of block = 0.188
Explanation:
Mass m = 5.6 kg
k = 1040
= 0.26
0.035 m ,
= 0
0.02 m
From work energy theorem
--------- (1)
Kinetic energy
------- (1)
Potential energy
------- (2)
Work done
W = F.s ------ (3)
From Newton's second law
= mg
= 5.6 × 9.81 = 54.9 N
Friction force = 0.4 × 54.9 = 21.9 N
Now the work done by the friction
= - 21.9 × 0.015
= - 0.329 J
Now kinetic energy
At point 1
0.637 J
At point 2
Potential energy
J
From equation (1) we get
0 + 0.637 - 0.329 = 2.8 + 0.208
2.8 = 0.1
0.188
This is the velocity of block.