Question

if a ball is thrown at an angle theta from horizontal with speed v then we know that it will land with same speed at horizontal.So if we calculate change in velocity when it lands on surface again then the change in velocity is -2vsin thetajcap. but it should be zero as landing launching speed are same. So why change in velocity is not zero

Answer 1

Answer:

• PLEASE read these then see image ....

• Your answer is in your question..

• Speed will be zero because magnitude is same
• but velocity would not be equal to Zero as it depends on direction(vector quantity)

• So to find change in any vector quantity direction is must to be seen....

• Here in X component velocity will remain same ucostheta icap .....

• But y component of initial Velocity is usintheta jcap(in the direction of positive y )

• But y component of Final velociy will be in usintheta -jcap ( in the -y direction ) ....

• hence the direction is opposite.

( see in the image )