Question

The lob in tennis is an effective tactic when your opponent is near the net. It consists of lofting the ball over his head, forcing him to move quickl

Other
ANSWERED
asked 2021-02-25
The lob in tennis is an effective tactic when your opponent is near the net. It consists of lofting the ball over his head, forcing him to move quickly away from the net (see the drawing - I am sorry that I am not able to provide the drawing at this time as my scanner is broken). Suppose that your loft the ball with an initial speed of 15.0 m/s, at an angle of 50.0 (degrees) above the horizontal. At this instant your opponent is 10.0 m away from

Answers (1)

2021-02-26

image
The components of the velocity are \(\displaystyle{v}_{{{o}{y}}}={v}_{{o}}{\sin{{50}}}={15}{\sin{{50}}}={11.5}\ \frac{{m}}{{s}}\)
\(\displaystyle{v}_{\otimes}={v}_{{o}}{\cos{{50}}}={9.64}\ \frac{{m}}{{s}}\) The time taken by the ball to reach the point P ' is
\(\displaystyle{S}={v}_{{o}}{y}{t}-{\left({\frac{{{1}}}{{{2}}}}\right)}{>}^{{2}}\)
\(\displaystyle{0}{r}{2.10}={11.5}{t}-{\left({\frac{{{1}}}{{{2}}}}\right)}{\left({9.8}\right)}{t}^{{2}}\)
\(\displaystyle{4.9}{t}^{{2}}-{11.5}{t}+{2.1}={0}\)
This Quadractic equation in t, is solved for the values of t
\(\displaystyle{t}={2.15}\ {s}\) and 0.2 s
as the opponent begins to move only after 0.3s later, we taket = 2.15s
Therefore, he catches the ball at time t'=(2.15-0.3)s
The total horizontal distance
\(\displaystyle{x}={v}_{\otimes}\cdot{t}\)
\(\displaystyle{\left({10}+{x}\right)}={v}_{\otimes}\cdot{2.15}{s}\)
\(\displaystyle={9.64}\cdot{2.15}'\)
The value of ' x ' is calculated.
Thus the required speed of the opponent \(\displaystyle{v}={\frac{{{x}}}{{{t}'}}}\)

0
 
Best answer

expert advice

Have a similar question?
We can deal with it in 3 hours

Relevant Questions

asked 2021-03-12
A 75.0-kg man steps off a platform 3.10 m above the ground. Hekeeps his legs straight as he falls, but at the moment his feettouch the ground his knees begin to bend, and, treated as aparticle, he moves an additional 0.60 m before coming torest.
a) what is the speed at the instant his feet touch theground?
b) treating him as a particle, what is his acceleration(magnitude and direction) as he slows down, if the acceleration isassumed to be constant?
c) draw his free-body diagram (see section 4.6). in termsof forces on the diagram, what is the net force on him? usenewton's laws and the results of part (b) to calculate the averageforce his feet exert on the ground while he slows down. expressthis force in newtons and also as a multiple of his weight.
asked 2021-02-19
A 10 kg objectexperiences a horizontal force which causes it to accelerate at 5 \(\displaystyle\frac{{m}}{{s}^{{2}}}\), moving it a distance of 20 m, horizontally.How much work is done by the force?
A ball is connected to a rope and swung around in uniform circular motion.The tension in the rope is measured at 10 N and the radius of thecircle is 1 m. How much work is done in one revolution around the circle?
A 10 kg weight issuspended in the air by a strong cable. How much work is done, perunit time, in suspending the weight?
A 5 kg block is moved up a 30 degree incline by a force of 50 N, parallel to the incline. The coefficient of kinetic friction between the block and the incline is .25. How much work is done by the 50 N force in moving the block a distance of 10 meters? What is the total workdone on the block over the same distance?
What is the kinetic energy of a 2 kg ball that travels a distance of 50 metersin 5 seconds?
A ball is thrown vertically with a velocity of 25 m/s. How high does it go? What is its velocity when it reaches a height of 25 m?
A ball with enough speed can complete a vertical loop. With what speed must the ballenter the loop to complete a 2 m loop? (Keep in mind that the velocity of the ball is not constant throughout the loop).
asked 2021-02-16
A quarterback claims that he can throw the football ahorizontal distance of 183 m (200 yd). Furthermore, he claims thathe can do this by launching the ball at the relatively low angle of 30.0 degree above the horizontal. To evaluate this claim, determinethe speed with which this quarterback must throw the ball. Assumethat the ball is launched and caught at the same vertical level andthat air resistance can be ignored. For comparison, a baseballpitcher who can accurately throw a fastball at 45 m/s (100 mph)would be considered exceptional.
asked 2021-05-16
Look Out! A snowball rolls off a barn roof that slopes downward at an angle of 40 degrees . The edge of the roof is 14.0 m above the ground, and the snowball has a speed of 7.00 m/s as it rolls off the roof. Ignore air resistance.
A man 1.9 m tall is standing 4.0 m from the edge of the barn. Will he be hit by the snowball?
...