Answer:
The direction of the B-field is in the +y-direction.
Explanation:
The corresponding formula is

This means, we should use right-hand rule.
Our index finger is pointed towards +x-direction (direction of velocity),
our middle finger should point towards the direction of the B-field,
and our thumb should point towards the +z-direction (direction of the force).
Since our middle finger in this situation points towards +y-direction, the B-field should be in +y-direction.

Answer:
See the answer below
Explanation:
1. Speed is calculated as the ratio of distance and time. Hence, Jame's speed can be calculated as:
400/5 km/hr = 80 km/hr
The unit for the speed would be km/hr. This can also be converted to m/s:
80 km = 80,000 m
1 hr = 3,600 s
80 km/hr = 80,000/3600 m/s = 22.22 m/s
2. Since James drove 400 km in 5 hours, the distance he drove is 400 km.
3. The time it took for James to get there is 5 hours.
Newton's 2nd law of motion:
Force = (mass) x (acceleration)
= (0.314 kg) x (164 m/s²)
= 51.5 newtons
(about 11.6 pounds).
Notice that the ball is only accelerating while it's in contact with the racket. The instant the ball loses contact with the racket, it stops accelerating, and sails off in a straight line at whatever speed it had when it left the strings.
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