Prelim_Solutions__1_F04

Prelim_Solutions__1_F04 - W sin θ = ma x ⇒ a x = N W sin...

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Prelim Exam #1 - Solutions Fall 2004 1. (a) C (b) 1 year = (365 days) 24 hr 1 day 3600 s 1 hr ~ 3 × 10 7 s distance ~ 4 × 10 7 m & speed ~ 1 m/s t ~ 4 × 10 7 m 1 m/s = 4 × 10 7 s But we have to sleep sometime, so t ~ 10 8 s ~ 30 years. 2. C 3. A, D 4. (a) D (b) E 5. A 6. (a) B (b) C 7. (a) (b) a 3 ( Δ t) 2 = 3.0 m a 3 = 3.0 m (0.25 s) 2 = 12 m/s 2 8. (a) v x (t) v y (t) t 0 t 0 a x (t) a y (t) t 0 t 0 (b) D = v ox t v ox = D t = 0.80 m 0.80 s = 1.0 m/s 2 3 4 v 23 Δ t 34 v Δ t a 3 ( Δ t) 2 v 23 Δ t -
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(c) y = y o + v oy t - 1 2 gt 2 (d) v oy = y - y o t + 1 2 gt = 0 - 1.20 m 0.80 s + 1 2 (9.8 m/s 2 )(0.80 s) = - 1.5 m/s + 3.92 m/s = 2.4 m/s 9. (a) (b) y( ): Σ F y = ma y T cos θ - w = T cos θ - mg = 0 T = mg cos θ = (80 kg)(9.8 m/s 2 ) cos40° = 1020 N 1000 N (c) R = D 2 + L sin θ = 3.0 m + (4.0 m) tan40° = 6.4 m x( ): Σ F x = ma x T sin θ = m v 2 R mg cos θ sin θ = m v 2 R v = gR tan θ = (9.8 m/s 2 )(6.4 m) tan40° = 7.3 m/s period = 2 π R v = 2 π (6.4 m) 7.3 m/s = 5.5 s 10. (a) (b) (c) (d) N Wedge Block (e) m: y( ): N W cos θ - mg = ma y = 0 N W = mg cos θ x( ): N
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Unformatted text preview: W sin θ = ma x ⇒ a x = N W sin θ m = mg cos θ sin θ m = g tan θ m + M: y( ↑ ): N T- Mg - mg = (m + M)a y = 0 ⇒ N T = (m + M)g ⇒ f k = μ k N T = μ k (m + M)g x( → ): F Hand- f k = (m + M)a x ⇒ F Hand = f k + (m + M)a x = μ k (m + M)g + (m + M)g tan θ = (m + M) g (μ k + tan θ ) w Earth on Seat + Passenger T Cable on Seat (tension) θ (gravitational) mg θ (gravitational, due to Earth) N Wedge (normal contact) Mg θ (gravitational, due to Earth) N Block (normal contact) (normal contact) k Table f (friction) Hand F N Table (normal contact) (normal contact) Hand F k Table f (friction) N Table (normal contact) Mg mg (gravitational, due to Earth) t w...
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This note was uploaded on 03/27/2008 for the course PHYS 1112 taught by Professor Leclair,a during the Spring '07 term at Cornell.

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Prelim_Solutions__1_F04 - W sin θ = ma x ⇒ a x = N W sin...

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