The radius of the sphere in meters is ,r =
Think about the angle the ground and the shadow make. Since the sun's beams are parallel, the angle created by the stick's shadow is also equal. Since the stick is 1 m high and its shadow is 2 m long, we know that the stick's angle is arctan 1/2. Therefore, by thinking of a right-angled triangle,
r/10 = tan [arctan(1/2)] = tan (1/2)
Since, tan (θ/2) = 1-cos(θ) / sin(θ)
we find that,
r/10 = 
Hence, r = 
So, the radius of the sphere in meters is ,r =
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Motion of a ball thrown by a person upwards and caught after some time is an example of motion in which displacement of the particle is zero but acceleration is not zero in journey.
The displacement of the ball is zero because the starting and end point of the motion are same, i.e, the person's hands.During its motion, the acceleration of ball is constant and non zero called as acceleration due to gravity, g= -9.8 m/s². The velocity of ball is continuously changing. It first decreases during the upward motion of the ball and then increases during the downward journey.The acceleration remains constant and non zero all the time.
Answer:
Second Trial satisfy principle of conservation of momentum
Explanation:
Given mass of ball A and ball B 
Let mass of ball
and
Final velocity of ball 
Final velocity of ball 
initial velocity of ball 
Initial velocity of ball 
Momentum after collision 
Momentum before collision 
Conservation of momentum in a closed system states that, moment before collision should be equal to moment after collision.
Now, 
Plugging each trial in this equation we get,
First Trial

momentum before collision
moment after collision
Second Trial

moment before collision
moment after collision
Third Trial

momentum before collision
moment after collision
Fourth Trial

momentum before collision
moment after collision
We can see only Trial- 2 shows the conservation of momentum in a closed system.
Answer:
B
Explanation:
Forces are pushes or pulls. They can be balanced or unbalanced. If unbalanced they can change the shape of objects and change the way they are moving (speed-wise)
Answer: 1
Explanation:
Given
Tension is the string 
mass of object 
Tension is greater than the weight of the object i.e. elevator is moving upward
we can write
