A few days ago
Anonymous

Projectile Motion Word Problem???

Jack be nimble, Jack be quick, Jack jumped over the candlestick with a velocity of 5.0 m/s at an angle of 30.0° to the horizontal. Did Jack burn his feet on the 0.25 m-high candle?

If you could just tell me how to get started, what equations to use, etc. that’d be great!

Thanks!

Top 2 Answers
A few days ago
Anonymous

Favorite Answer

If Jack starts from (0,0) with co-ordinates in metres, his position at time t sec. when he reaches the candlestick with its base at (x, 0) is given by:

x = 5t cos(30) …(1)

y = 5t sin(30) – gt^2/2 …(2)

From (1):

t = x / 5cos(30) = 2x / 5sqrt(3)

Substituting this in (2):

y = x / sqrt(3) – 4gx^2 / 75.

If y >= 0.25 plus clearance needed to avoid burning, Jack will be safe, but the question gives no value for x.

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4 years ago
?
Pointy goofed up one difficulty:  he forgot to multiply the fee of the ball by cos ? to get carry of the horizontal speed. d = V² sin 2?/g = a hundred and twenty feet V = ?(a hundred and twenty feet * 32.2 feet/sec² / (?3/2) ) V = sixty six.8 feet/sec t = a hundred and twenty feet / (V * cos ?) = a hundred and twenty feet / (sixty six.8 * ?3/2) = 2.07 sec
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